METHOD FOR DETECTING BLOCKAGE IN A FLUID FLOW VESSEL

Abstract

A method for determining stenosis of the carotid artery in a human patient consisting of a first step of placing a sensing device comprising an array and three sensing elements onto the patient, wherein a first sensing element is placed near the heart and the two remaining sensing elements are placed adjacent to the carotid arteries; the sensing elements then measure sounds from each of the three sensing elements, resulting in sound from three channels. The sound is measured in analog and modified to digital format and then each of the three channels are analyzed before a power spectral density analysis is performed. The power spectral density graph reveals peaks that are not due to noise that are then analyzed to provide for a calculation of percent stenosis or complete occlusion of the carotid artery.

Claims

1. A method for measuring sound from vortices in a carotid artery comprising: a. performing a first quality control procedure on at least two sensing elements, wherein said first quality control procedure is performed by playing a predetermined set of tones within a base unit, wherein said at least two sensing elements detect said set of tones and wherein said detected set of tones are compared to said predetermined set of tones, wherein the sensing elements are replaced if the comparison between said detected set of tones and said predetermined set of tones has a frequency variance of more than 10%; b. performing a second quality control procedure on the at least two sensing elements, wherein said second quality control procedure is performed by detecting sounds of blood flow through the carotid artery and comparing said detected sounds to a predetermined sound signature, wherein the sensing element is repositioned if the detected sounds compared to the predetermined sound signature have a second frequency variance of more than 25%, wherein if the second frequency variance in the second quality control procedure is more than 100%, step (a) is repeated; and c. detecting sounds generated by the vortices in the carotid artery for at least 30 seconds.

2. The method of claim 1 wherein the sounds detected from the vortices in the carotid artery are detected at between 40 Hz and 3,000 Hz.

3. The method of claim 1 wherein a further step (d) comprises eliminating sounds from the carotid artery that are outside of the range of 40 Hz to 3,000 Hz.

4. The method of claim 3 comprising a further step (e) comprising generating a power spectral density graph of the sounds from step (d).

5. The method of claim 1 comprising three sensor elements.

6. The method of claim 3 further comprising: e. downsampling the detected sounds from step (c) from analog to digital at a sampling rate of 20 kHz.

7. The method of claim 4 comprising a further step (f) of determining a percent stenosis from at least one peak in said power spectral density graph by calculating (1−f.sub.1/f.sub.2)×100.

8. The method of claim 1 wherein in step (a) if the comparison between said detected set of tones and said predetermined set of tones has a variance of more than 10% relative to frequency, then the sensing element needs to be replaced.

9. The method of claim 1 wherein in step (b) the sensing element is repositioned if the detected sounds compared to the predetermined sound signature have a variance of more than 25% relative to frequency.

10. The method of claim 8 wherein if the variance in the second quality control procedure is more than 100% relative to frequency, then step (a) is repeated.

11. A method of detecting an occlusion in a fluid flow vessel comprising: a. placing a sensor pod having a listening device onto said fluid flow vessel; b. detecting sounds passing through said fluid flow vessel; c. performing wavelet analysis and removing low frequency sounds below 60 Hz; d. performing Burg's Method, Welch's method, or both to denoise the data; e. plotting a power spectral density plot of the frequency in the x-axis and intensity in the y-axis to generate at least two primary peaks in the power spectral density plot; f. calculating the primary two peaks in the power spectral density plot; and g. determining an occlusion percentage of the fluid flow vessel by calculating (1−f.sub.1/f.sub.2)×100.

12. The method of claim 11 comprising performing a first quality control procedure on said listening device before step (a) comprising: a1. playing a predetermined sound signature from a base; a2. detecting said sound signature with said listening device; a3. comparing said detected sound signature to the predetermined sound signature; and a4. confirming proper function of the listening device if the difference between the frequency of the detected sound and the predetermined sound signature is 10% or less.

13. The method of claim 11 wherein the sounds detected passing through said fluid flow vessel are detected at between 40 Hz and 3,000 Hz.

14. The method of claim 11 wherein step (b) comprises eliminating sounds detected passing through said fluid flow vessel that are outside of the range of 40 Hz to 3,000 Hz.

15. The method of claim 11 further comprising downsampling the detected sounds from step (c) from analog to digital at a sampling rate of 20 kHz.

16. A method of detecting an occlusion in an arterial vessel comprising: a. placing a sensor pod having a listening device on the skin of a patient adjacent to said arterial vessel; b. detecting sounds passing through said arterial vessel; c. performing wavelet analysis and removing low frequency sounds below 60 Hz; d. performing Burg's Method, Welch's method, or both to denoise the data; e. plotting a power spectral density plot of the frequency in the x-axis and intensity in the y-axis to generate at least two primary peaks in the power spectral density plot; f. calculating the primary two peaks in the power spectral density plot; and g. determining stenosis of the arterial vessel by calculating (1−f.sub.1/f.sub.2)×100.

17. The method of claim 16 wherein said arterial vessel is a carotid artery or a coronary artery.

18. The method of claim 16 comprising performing a first quality control procedure on said listening device before step (a) comprising: a1. playing a predetermined sound signature from a base; a2. detecting said sound signature with said listening device; a3. comparing said detected sound signature to the predetermined sound signature; a4. confirming proper function of the listening device if the difference between the frequency of the detected sound and the predetermined sound signature is 10% or less; and a5. performing a second quality control procedure on said listening device wherein said second quality control procedure is performed by detecting sounds of blood flow through the arterial vessel and comparing said detected sounds to a predetermined sound signature, wherein the listening device is repositioned if the detected sounds compared to the predetermined sound signature have a second frequency variance of more than 25%, wherein if the second frequency variance in the second quality control procedure is more than 100%, step (a) is repeated.

19. The method of claim 18 wherein detecting sounds of blood flow through the arterial vessel is detecting the detected sounds at a frequency of between 60 Hz and 260 Hz.

20. The method of claim 16 wherein the calculation of stenosis is a binary calculation of greater than or less than 50% stenosis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0097] FIG. 1 depicts a ring vortex.

[0098] FIG. 2 depicts a ring vortex.

[0099] FIG. 3 depicts a ring vortex.

[0100] FIG. 4 depicts a ring vortex.

[0101] FIG. 5 depicts a ring vortex.

[0102] FIG. 6 depicts a partial exploded view of a sensor array and piezo pods.

[0103] FIG. 7 depicts an exploded view of a sensor array and piezo pods.

[0104] FIGS. 8A and 8B depict an exploded view of a piezo pod with bellows membrane.

[0105] FIG. 9 depicts various views of a sensory array with piezo pods attached.

[0106] FIG. 10 depicts the movement of a bellows membrane on a piezo pod.

[0107] FIG. 11 depicts a sensor array on a person.

[0108] FIG. 12 depicts a side and sectional view of a bellows piezo pod.

[0109] FIG. 13 depicts a rear neck sensor array and two attached slideable sensor pods.

[0110] FIG. 14 depicts a front view of a rear neck sensor array and two attached slideable sensor pods.

[0111] FIG. 15 depicts an alternative view of FIGS. 8 and 9.

[0112] FIG. 16 depict an alternative sensor array and sensor pods secured on the array, with a partial exploded view of certain disposable components.

[0113] FIG. 17 depicts an exploded view of a sensor pod having sliding means on an array.

[0114] FIG. 18 depicts a cross-sectional view of a slideable sensor pod.

[0115] FIG. 19 depicts a disposable sensor pod with pin mount.

[0116] FIG. 20 is a view of two piezos without an array.

[0117] FIG. 21 is a side view of a piezo without an array.

[0118] FIG. 22 depicts a sensor paid with a curved, concave piezo.

[0119] FIG. 23 depicts a concave piezo.

[0120] FIG. 24 depicts nonsymmetrical sensor pads.

[0121] FIG. 25 depicts a base.

[0122] FIG. 26 array on a base

[0123] FIG. 27 depicts an example of a sensor pod having attached indicators.

[0124] FIG. 28 details a flowchart of a quality control process.

[0125] FIG. 29 details a sample GUI.

[0126] FIG. 30 details an example of light indicators indicating after a test.

[0127] FIG. 31 details a flowchart of an active quality control procedure.

[0128] FIG. 32 depicts a passive cancellation device with “over-the-ear” like construction, to block ambient noise from the sensor.

[0129] FIG. 33A depicts an electronic view of subtracting ambient noise from a received signal.

[0130] FIG. 33B depicts a flowchart of subtraction of ambient noise from a signal.

[0131] FIG. 33C depicts a flowchart of an active noise cancellation process.

[0132] FIG. 34A depicting a double piezo assembly.

[0133] FIG. 34B depicting a parallel piezo assembly.

[0134] FIG. 34C depicting a microphone on an array.

[0135] FIG. 34D depicting a microphone on a base.

[0136] FIG. 34E depicting a microphone on a cart.

[0137] FIG. 35 depicts a sensor pod assembly with sound attenuating materials.

[0138] FIGS. 36, 37, and 38 depicts a flowchart data collection, with FIG. 36 for a wired connection, FIG. 37 for wireless connection from a single module, and FIG. 38 for wireless connection from multiple modules.

[0139] FIG. 39 depicts a chart showing a frequency chart.

[0140] FIG. 40 depicts certain raw data from three channels.

[0141] FIG. 41 depicts a ten second channel plot.

[0142] FIG. 42 depicts a PSD periodogram

[0143] FIG. 43 depicts Welch's power spectral density estimate.

[0144] FIG. 44 depicts additional data plot of Welch's method.

[0145] FIG. 45 depicts Burg's Method of smoothing.

[0146] FIG. 46 depicts Reflection Coefficients.

[0147] FIG. 47 depicts a PSD before denoising.

[0148] FIG. 48 depicts a PSD before denoising.

[0149] FIG. 49 depicts a PSD before denoising.

[0150] FIG. 50 depicts a Burg's power spectral density estimate.

[0151] FIG. 51 depicts a Parametric PSD after denoising, depicting peaks.

[0152] FIG. 52 depicts a perturbation representative in an artery.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0153] The embodiments of the invention and the various features and advantages thereto are more fully explained with references to the nonlimiting embodiments and examples that are described and set forth in the following descriptions of those examples. Descriptions of well-known components and techniques may be omitted to avoid obscuring the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those skilled in the art to practice the invention. Accordingly, the examples and embodiments set forth herein should not be construed as limiting the scope of the invention, which is defined by the appended claims.

[0154] As used herein, terms such as “a,” “an,” and “the” include singular and plural referents unless the context clearly demands otherwise.

[0155] All patents and publications cited herein are hereby fully incorporated by reference in their entirety. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that such publication is prior art or that the present invention is not entitled to antedate such publication by virtue of prior invention.

[0156] The embodiments contemplate devices, systems, and methods for determining blockage in a fluid flow vessel. To reliably determine fluid flow, we need to determine that the components of the device are working properly, are clean and sanitary, are positioned in the correct locations for detection. Furthermore, the device needs to passively prevent ambient noise from entering the sensing device. However, active noise cancellation strategies can further eliminate ambient noise. Finally, processing strategies can be utilized to filter the collected data and to break it apart into useable packets of data for determination of occlusion in a fluid flow vessel.

[0157] For many cases, fluid flow vessels include the arterial circulatory system, for example the carotid artery, but also the arteries of the heart, the coronary arteries. However, flow through industrial pipes can also be evaluated using the devices and methods described herein.

Description of Ring Vortices being Detected

[0158] FIG. 1 is the side view of a ring vortex showing the rotation of the core, the velocity of the motion of the center of the core (u′), and the diameter of the vortex (d). In a carotid artery, the diameter of the vortices is initially equal to the diameter of the stenosed region. This is followed by a second region in which the diameter is equal to the inside diameter of the artery. Note that the core is thin compared to the radius of the entire ring. Inside the core, the blood molecules rotate as shown by FIG. 1 in circular or near circular (elliptical) motion around the center of the core. A blood molecule farther from the center rotates at higher velocity than one which is closer to the center. This is similar to a solid disk. The rotational motion is coherent, which maintains the same angular velocity without friction between particles at different distances from the center. This solid like motion eliminates internal frictional, dissipative forces, which if they existed would diminish the energy of the rotation quite rapidly. In such a case, the vortices would not travel nearly as far, turning to full turbulence at shorter distance of motion.

[0159] The ring vortices are produced equidistant from each other at a distance between them equal to their diameter as they move downstream, as illustrated in FIG. 2 which shows the formation of ring vortices upon the exit of air from a long tube. In this well-known experiment, air is being blown from a cylinder due to the motion of a piston within the cylinder. As the air departs the cylinder at sufficient velocity, ring vortices in the emerging air are formed and remain at the same diameter and distances between adjacent vortices for the entire distance that they travel. They will later dissipate into smaller eddies, which is called full turbulence. As the ring vortices pass the flame, the high speed of the air within the core of the ring vortices will blow out the flame. The air ring vortices are sufficiently stable to travel a distance of 10-20 times the distance between the individual rings. The arrows above and below the cylinder shows that air spreads out as it leaves the cylinder because there are no containing walls. Yet the diameter of the rings does not increase as they move toward the flame. Within the carotid artery, the medium is blood rather than air, but the behavior is the same if the Reynolds number is the same. In the artery blood is not free to expand beyond the size of the artery, however, the size of the vortices in the flow of blood remains the same diameter as the orifice (stenosis) opening, even though the size of the artery is larger than the diameter of the vortices. In FIG. 2 which illustrates vortices in air the size of the vortices is a small percentage larger than the size of the cylinder opening. In the flow of blood in which the flow is restricted to the size of the artery rather than being free to expand, the size of the vortices is the same as the size of the jet emerging from the stenosed section of the artery. Note that the most recent vortex formed is at a distance of approximately one vortex diameter from the orifice. A microphone placed to the side of the vortex flow will measure sound at a frequency given by the frequency in which the vortices pass in front of the microphone. Sound is produced by the vortices because the rapid motion of molecules inside the ring is highly organized, that is nonrandom, which causes lower pressure at the surface of each individual vortex ring. This lower pressure at the surface of the vortex ring followed by a higher pressure between the vortex rings, causes sound to be transmitted to the microphone. This is the same principle as occurs in the passage of ring vortices within a blood vessel [Mollo-Christensen, Kolpin, and Marticcelli, “Experiments on jet flows and jet noise far-field spectra and directivity patterns,” Journal of Fluid Mechanics 1964, vol. 18, no. 2, 285-301]. Note the sound is produced in a direction perpendicular to the motion of the ring vortices, along the axis of the artery.

[0160] In FIG. 3, [Johansen 1930, FIG. 8 of “Flow through pipe orifices at low Reynolds numbers,” Proceedings of the Royal Society A, vol. 126, 231-245] is a photograph of blood flow below the critical value. This Reynolds Number (RE) equals vD/η=600, where v is blood velocity, D is diameter of artery, and η is blood kinematic viscosity (equals 0.035 cm.sup.2/s at human temperature). Flow is from left to right. Note that there are no ring vortices yet formed since the velocity of the blood is too low as in the diastolic phase of the cardiac cycle and latter part of the systole. There are however small striations which occur at RE lower than the critical value, but vortex rings do not yet form.

[0161] At RE less than 800 or greater than 2,100, ring vortices do not form. The closer to 800 while still remaining below 800, the more string-like motions are seen, as seen in FIG. 3. At greater than 2,100, the vortices breakup into small eddies with random orientations [Johansen 1930]. FIG. 4, [Becker & Massaro, FIG. 5, number 2 of “Vortex evolution in a round jet” Journal of Fluid Mechanics 1968, vol. 31, part 3, 435-448] shows three ring vortices emerging from an orifice. Note that the ring vortices without confining walls disintegrate into small eddies after only three ring vortices. Also note that the diameter of the ring vortices remains constant and the distance between adjacent vortices is equal to the diameter of a single vortex.

[0162] FIG. 5, [Johansen 1930, FIG. 8] shows the blood flow pattern including ring vortices when the RE is 1,000, which is above the critical value for ring vortices to be formed. The blood flow is from left to right, the transition region from smaller diameter vortices to larger occurs rapidly in less than the distance between two of the larger vortices. The centers of all vortices, small or large, travel at the same speed. We call the first region, with smaller diameter vortices, Region I. The region of the larger vortices we call Region II. Region III follows Region II, where the vortices have disintegrated into small eddies. Because the vortices in Region I are closer together a higher sound frequency is produced, which we call f.sub.2, than is produced by the larger vortices which have a larger distance between them which produce lower sound frequency, f.sub.1. The diameter of the small vortices matches the diameter of the stenosed region. The diameter of the large vortices matches the diameter of the blood vessel in the non-stenosed region. The ratio of the two frequencies is the same as the ratio of the diameters, from which percentage stenosis can be determined. Variations from one patient to another in diameter of artery, velocity of blood, blood viscosity, temperature, and other variables cancel when taking the ratio of the two frequencies. In each heart cycle, the velocity rises above critical value during systole, and drops below critical value during diastole. Typical values for the Internal Carotid Artery (ICA) at Peak Systolic Velocity (PSV) range from velocity of 64-77 cm/s and diameter of ICA between 0.511 cm (for men) and 0.466 cm (for women) yield RE equal to 852 (for men) and 1,124 (for women), well within the range that produces ring vortex flow in the ICA. Also, the ring vortices only appear during the deceleration phase of the systolic part of the heart cycle that is following the moment of peak systolic velocity. Using the formulas given on by Becker and Massaro [1968, pg. 446],

[00001]$f\times \frac{d}{v}=0.0122\sqrt{RE},$

where v is the blood velocity, d is the diameter of the vortices, and f is the observed frequency seen at the microphone placed over the artery. Typical values of the solution of this equation at 50% stenosis yields f.sub.1=178 Hz and f.sub.2=356 Hz with a similar formula from other authors also quoted by Becker and Massaro [1968, pg. 446], one obtains f.sub.1=236 Hz and f.sub.2=472 Hz. Different patients at 50% stenosis could have different values of frequency for the two peaks, but they will remain at the same proportionality.

[0163] If no f.sub.1 appears in the PSD (between 60 Hz and 260 Hz), there was insufficient energy in the flow emerging from the stenotic region for the vortices to reach Region II, in which the larger vortices appear, at the lower frequencies. This indicates the artery is heavily stenosed. If there is no f.sub.2, there is an insufficient amount of stenosis to create the smaller vortices (Region I) indicating a low level of stenosis (below 15%) as reported by Khalifa and Giddens [“Characterization and evolution of poststenotic flow disturbances,” Journal of Biomechanics 1981, vol. 14, no. 5, pg. 292] who report that below 25% reduction in area due to stenosis (which corresponds to a reduction of 13% in diameter), no signal is picked up. If there is neither f.sub.1 nor f.sub.2, the indication is that there is a near blockage level of stenosis, as the vortices cannot be produced even when the velocity is sufficient to give RE between 800 and 2,100.

[0164] To measure the large ring vortices, we need to ensure that the device we are using contains properly sterile and functioning elements. Described herein are certain disposable components, methods for determining proper function of these elements, and methods for eliminating and reducing noise from the data sample in order to accurately and efficiently measure and quantify stenosis in the arterial circulatory system.

[0165] Furthermore, these aspects and teachings can be applied into industrial structures. For example, these same perturbations that are present in industrial piping, such as fluid flow in gas and oil industries, production of fats, oils, and other consumer goods, chemical and biological production, and the like. Representative perturbations are depicted, for example in FIG. 52. Accordingly, the device can be utilized to identify and quantify percent blockage within a fluid flow vessel, whether that is in the arterial circulatory system or whether it is within an industrial pipe or tube.

[0166] Replacement components provide for accurate and clean components that ensure greater chance of accuracy and reproducibility. Piezoelectric sensors have a variety of potential uses, but as described herein, they are being utilized as a contact microphone. The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. Detection of pressure variations in the form of sound is the most common sensor application, e.g., acting as a microphone, wherein the sound waves bend the piezoelectric material creating changing voltage. Accordingly, the piezo sensor can be placed on or near a sound to receive the sounds.

[0167] Piezo sensors are especially used with high frequency sound in ultrasonic transducers for medical imaging and industrial nondestructive testing. However, piezo sensors are also frequently used for the detection and activation of a device, based on the ability to receive a signal and to then send an electronic signal, thereby acting as the actuator. In the embodiments herein, piezoelectric sensors (“piezo”) are utilized for their ability to detect certain frequency sounds or vibrations caused by the distortion of a fluid flow vessel, specifically of the arterial circulatory system.

[0168] Because of the sensitivity of these sensors, piezoelectric sensors can be somewhat fragile and can be broken from both normal use and misuse. Furthermore, as utilized in a medical device, there is the inherent need to ensure accuracy of each of the three piezoelectric sensors. Accordingly, any slight modification of the sensor may result in a modification of the input received and thus would result in erroneous data.

[0169] Replacement components may be one of three different components as described herein. A first component may be a disposable piezo assembly, a second component may be a sensor pod, which comprises the disposable piezo assembly and a sensor base, and a third component may be a disposable array, comprising one or more sensor pods. In this manner, each component may be disposable to allow for easy replacement after use.

[0170] Piezo sensors can include any number of materials. Typically, however, the sensor contains a portion of ceramic material and a metallic component. Piezo sensors may also use a polymer film configuration which exhibits a low acoustic impedance similar to that of human tissue or made of metallic materials. These sensors, as used in the invention herein, are typically a circular shape with a diameter of about 3 inches. Typical piezos have a diameter from about 0.01 inch to about 6 inches for use in medical settings, with most typical sizes between about 0.5 inch to about 4 inches in diameter. For most applications, including industrial settings, a range of 0.01 inch to about 12.0 inches is preferred, wherein the size of the piezo is generally related to the diameter of the fluid flow vessel to be measured. In preferred embodiments, the fluid flow vessels are veins and arteries in the body, for which a 4.0-inch or smaller diameter piezo is preferable.

[0171] There is no inherent frequency limit for a piezoelectric sensor. However, the limits of applications are usually determined by resonances associated with the shape and/or the size of the transducer design. The piezo sensors utilized herein have a thickness of about 0.01 mm to 2.0 mm and are capable of detecting sounds between 10 Hz and 32 kHz and an amplitude of 0.0002 N/m.sup.2 to greater than 10 N/m.sup.2. In preferred embodiments, the piezos attached to a sensor pod detect sounds between about 20 Hz to 3,000 Hz, which are relevant toward measurements of fluid flow in the body. Typically, these sounds have an amplitude of between 0.002 N/m.sup.2 and 20 N/m.sup.2. While additional sounds are recorded, many of these sounds, i.e., the heartbeat and extraneous noise, are removed from the data set through several filters.

[0172] FIGS. 22 and 23 specifically depict a new piezo and mount. The piezo (602) is a concave piezo, made of metallic or polymeric materials. Curved cap (601) contains an outer rim, and an inner flange adjacent to a central opening having a similar size and shape to the piezo. The flange supports the piezo (602) which can be engaged with an adhesive (603).

[0173] In the broadest sense, the piezo sensors are disposed of within a pod. On one side of the piezo is placed a sensor pad, for example, those of (1, 2, 17 and 19). The sensor pad is then pressed against the skin or clothing of a patient to listen to the underlying circulatory system. The sensor pad allows for transmission of energy waves, sound, and vibrations, which are received by the piezo element. Gel or other impedance matching substance may be applied to the skin facing surface of the pad.

[0174] In view of FIG. 6, a sensor array is defined comprising a disposable sensor assembly (85), and a disposable sensor pad (18). These two features are replaced frequently, to prevent contamination and error. For example, the sensor can be placed on a patient as depicted in FIG. 11. The yoke (140, 130, and 3) is handheld by the patient during the test. Piezos wear over time and that damage can unfortunately occur from use. Because of the sensitive nature of the piezo, it is necessary to ensure that they are properly functioning before each use. Proper testing protocols utilize a program implemented through a computer, which generates a known set of sounds related to the sounds to be detected on the fluid flow vessel and matches the known played sound to the sounds detected and recorded in real-time by the sensor pods. Where the known sounds and detected sounds match, the sensor pod is confirmed to be working to specification. Wherein the sensor pod is not functioning properly, the system will sound an alarm, which will indicate to the operator the need to replace the disposable component. Accordingly, the piezos must be designed to allow for easy replacement of the piezo, while ensuring that the device maintains operation and reliability during ordinary use.

[0175] There are several ways in which the piezoelectric elements can wear or be damaged including ordinary and standard use of the device. Ordinary wear may occur as the piezoelectric element wears from ordinary and standard use, and after about 10 uses to about 400 uses, the piezoelectric element breaks down so that the function and the electrical currents generated are different when comparing the first use to the second, fifth, tenth, 25th, 50th, 75th, 100th, 200th, 300th, or 400th use and all numbers in between. Accordingly, to ensure that accurate results are received by each of the units, it is imperative to replace the unit that has worn to maintain consistent results.

[0176] Additional wear or breakage can occur to the piezoelectric sensors by error or accident. For example, human error may lead to the array being dropped, or placed onto the base in a manner that breaks, bends, or otherwise damages the piezoelectric unit. Further damage may occur as clean sensor pads are attached and placed against the piezoelectric sensor for use on a patient.

[0177] To ensure sanitary use of the device, the sensor pads are replaced between each use of the device. However, because the sensor pads are placed directly onto the piezoelectric unit, there is risk that human error may damage the piezoelectric sensor, either by too much force, or simply through improper pressure applied to the piezo when installing or removing a sensor pad.

[0178] Ordinary wear or accidental damage is tested through routine quality control procedures performed in a self-diagnosis module. The sensor pods can be placed in a base or holding device that comprises a speaker embedded within the base which provides a predetermined sound that can be measured by each piezoelectric sensor. When the sensor device is activated for use, the sound, which can include both audible and inaudible sound waves, is played for between about 1 second and about 20 seconds. During the time that the sound is playing, each of the piezoelectric sensors records the sound and a program then confirms that each of the three sensors is recording the appropriate sounds being played. If each of the three sensors detects the appropriate sounds, then the sensor device is ready for use. However, if one or more of the sensors detects sounds that do not match with the predicted sounds, the device will provide an alert, which may include lights, sounds, or other display elements, to alert the user of the device that one or more of the piezos needs to be replaced.

[0179] An optional display screen attached to the base can further display the device and identify the sensor pod containing the piezo that failed the QC test. Another manner for identifying the failed sensor is to have lights that correspond to working or failed tests either on the base or on the sensor array itself. Once the failed piezo is identified, the user can then replace one or more of the components, as described herein, and then perform the QC test again to ensure that the device is now ready for use.

[0180] Accordingly, in a preferred method, a piezo is replaced every 10 uses to ensure that there is no noticeable wear and tear on the piezo, and to prevent the possibility of erroneous data. Accordingly, the sensor device comprises a counter wherein the number of times that a test is run with each of the piezo is counted, so that the sensor device notifies a user that the piezo needs to be replaced, even if each of the piezos are working properly.

[0181] In other embodiments, the piezos can be replaced every 1, 2, 5, 10, 25, 50, 75 uses, 100 uses, 125 uses, 150 uses, about every 200 uses, or about every 400 uses or a number in between. The particular number of uses for each piezo will be determined through additional use of the devices in normal practices. However, to ensure sanitary and consistent results, it is preferred that the piezos are changed after no more than 100 uses.

[0182] To facilitate easy changing of the disposable piezo assembly (85), the disposable piezo assembly (85) is able to easily attach to an underlying disposable sensor base (86), and to be replaced. For example, a simple threaded attachment mechanism allows the sensor pod to be removed from the sliding sensor pod base, which is attached to the sensor array. Alternatively, quarter- or half-turn attachment means, magnetic attachment, and others as known to one of ordinary skill in the art are known.

[0183] FIG. 6 depicts a sensor array comprised of an inner array half (130) and an outer array half (140). The halves are secured together with threaded fasteners (134 and 133), though adhesives, snap fits, or plastic welding can be utilized for securing means. At the bottom of the array is a first sensor pod, depicting a locking cap (125) and a DBM (120) with a sensor pad (18) positioned on the obverse side, with a threaded fastener (133) securing said membrane in place. The DBM (120) is an elastomeric member, with or without articulating bellows geometry, containing an inner opening and an inner and outer flange, suitable to secure the DBM to an array, and to allow for the sensor pod to move freely on said array. The DBM (120) may also be attached to (130) or (140) via insert molding.

[0184] Near the vertex of the Y is a charging port (820) and a PCB charging contact (131) disposed therein. This allows the array to be placed into a charging port and charge a central battery.

[0185] Attached to the array is a sensor pod, made up of the components of a locking cap (125), a DBM (120), a PCB processor board (110), a PCB housing (115), a piezo cap (100), a piezo (90), and a disposable piezo assembly (85). These features are further detailed below. A disposable sensor pad (18) can be affixed to the piezo (90) via adhesives or by the natural adhesion of the pad material. For example, the piezo cap (100) can be attached to the PCB housing (115) in several ways, including as in FIG. 1 with a quarter turn feature, comprising a recess (101) and a locking feature (116) having corresponding openings to the pins on the piezo cap (100). By securing these together, the spring pin (111) is engaged and provides electrical contact between the components to power the piezo (90) from an internal power source. Features (101) and (116) can be swapped, provided they are maintained as a matching pair, to allow for selective attachment and detachment of the disposable piezo assembly (85). A recess is provided in the top of the piezo cap (100) for mounting the piezo (90) via pressure sensitive adhesive (92). The recess contains a flange which supports the circumference of the piezo (90) within the piezo cap (100). This recess also allows the piezo to sit about flush with the top of the piezo cap (10), for placement of the sensor pad (18).

[0186] FIG. 7 provides a further exploded view of FIG. 6. A disposable sensor pad (18) is provided to be attached to the disposable piezo assembly (85). The assembly (85) comprises a piezo wiring (91) which connects the piezo (90) to the PCB contact board (105). Two pressure sensitive adhesives (92) are provided, one connecting the piezo (90) to the piezo cap (100) and another adhesive (92) connecting the piezo cap (100) to the PCB contact board (105). These components make up the disposable assembly (85).

[0187] In one embodiment, this disposable assembly (85) is the smallest disposable component, which allows for quick and easy replacement of the piezo without replacement of any further components (except for the disposable sensor pad (18), which is replaced for every use). The disposable assembly (85) comprises a quarter turn locking feature (101) that corresponds to a paired feature (116) on the PCB housing (115). This allows for a small turn of the disposable assembly (85) to remove the component and replace. Additional attachment mechanisms can be easily exchanged, for example magnetic, threaded engagement, or simply a threaded fastener or two that can be engaged for replacement. Finger capable fasteners can use a full, half, or quarter twist to secure a fastener between two components. A person of skill in the art will recognize that numerous options exist for attaching and detaching such components and that attaching means incorporates these listed and additional options not described in detail herein.

[0188] The PCB housing contains a locking groove (117) that engages with and locks the elastomer DBM (120) to the PCB housing (115). In particular locking groove (117) engages locking key (121) between the locking cap (125) and the PCB housing (115). A locking cap (125) engages to a fastener (113) to secure the key (121). A second key (122) is also provided to lock the DBM (120) between the outer array housing (140) and the inner array housing (130). A further detail of these locking features is provided in FIG. 12.

[0189] While the disposable assembly (85) can be easily removed and replaced, it is also contemplated that the entire sensor pod can be removed and replaced easily. For example, removal of threaded fasteners (133) will allow for quick and easy replacement of the entirety of the pod, inclusive of the DBM (120). Furthermore, the DBM (120) can be held in place, and the locking cap (125) can reveal a threaded fastener (113) to replace the remaining components. In the figure, the fastener (113) can be oriented in either direction to allow for quick replacement.

[0190] FIG. 7 further details components of the array including a PCB charging contact (131), connecting a wiring harness (132) to each of the piezo sensors (90). A battery, not depicted, can be positioned within the array handle to power the devices, or can be attached directly to an AC or DC power source with a wire.

[0191] FIGS. 8A and 8B depict further exploded views of a sensor pod. FIG. 8A specifically defines a dual piezo mechanism, wherein a second piezo (150) is attached to the rear of the PCB processor board (110) to allow for noise canceling. Briefly, though described above, FIG. 8A depicts a piezo (90) a pressure sensitive adhesive (92), a piezo cap (100). The adhesive (92) engages the flange of the cap (100), and said flange supports the piezo (90) at its circumference. A second pressure sensitive adhesive (92) is positioned inside of the piezo cap (100) and engages to the PCB contact board (105), which contacts a PCB processor board (110). A second piezo (150) is engaged on the rear of the PCB processor board and a wiring (91) attaches the piezos to the PCB processor board (110). A threaded fastener (113) secures the PCB housing. The detail of the locking features (121 and 122) is best seen in a later figure. Sound locking holes (118) are depicted as well as the entrance hole (119) for the wiring harness (132).

[0192] FIG. 8B depicts a single piezo (90), a piezo wire (91), the adhesive (92). These combine into the piezo cap (100), which contains a locking feature (101). The second adhesive strip (92) attaches to the PCB contact board. The spring pin (111) is seen positioned to contact the PCB contact (106). A battery (112) is attached to the PCB board (110). A screw (113) attaches the PCB housing to the locking cap (125), which secures the DBM (120). The disposable piezo assembly (85) is combined with the sensor base (86) to form a sensor pod. Each of the disposable piezo assembly (85) and the sensor base (86) are replaceable or disposable, as needed.

[0193] FIG. 9 depicts several views of an array, with an angled sensor pad (18) positioned on each of the different sensor pods.

[0194] FIG. 10 depicts the possible movement of the DBM (120). The arrows (200) refer to spherical movement of the entire assembly, including the sensor pad (18), and the disposable piezo (85). The centerline (205) is provided, with all features moving in the direction of feature (210), both forward and backward, as necessary. In this manner, the DBM (120) allows for the entire feature of the sensor pad (18) and piezo (90) to press against a surface and extend away from the surface, but to return back to a central position after use. Furthermore, the spherical movement (200) allows for angular rotation to rotate and angle the sensor pad (18) to best fit against the skin surface of a patient, for example as depicted in FIG. 11. Here, a different sensor pad (36) is used against the skin surface on the neck, as compared to the sensor pad (18) at the torso. Appropriate pads, having different shapes can be used based on the needs of the particular patient.

[0195] FIG. 12 depicts a side profile and cross-sectional view through line A-A, of a sensor pod with DBM (120). The side profile shows a sensor pad (18) positioned above the piezo cap (100), PCB housing (115), the wiring harness (132) and the inner array (130) and outer array (140) connected with threaded fasteners (133). The cross-sectional view depicts a PCB housing (115) engaged to the piezo cap (100), with the adhesive (92) securing the piezo (90) at the righthand side. The lefthand side depicts the inner array (130) secured to the outer array (140) with a fastener (133). By compressing these together, the elastomer DBM (120) is compressed together. For example, the locking feature (122) is depicted securing the edge of the membrane (120) between the inner array (130) and the outer array (140). The inner locking feature (121) is secured between the PCB housing (115) and the locking cap (125). A fastener (113) is provided therein. Each side is similar through the cross-sectional view.

[0196] The DBM (120) is a circular feature having an inner opening. At the outer edge of the DBM (120) is an outer flange (122). At the circumference of the inner opening, there is an inner flange (121). These flanges (122 and 121) are used to lock the DBM (120) into place between the array features (130 and 140), as well as between the locking cap (125) and the housing (115).

[0197] Therefore, the DBM (120) is an elastomeric material, capable of allowing the attached piezo to flex in any direction, as well as move away from the surface to be compressed. This allows for a consistent pressure to be applied to the skin surface by the sensor pad (18), based on the rigidity of the membrane (120).

[0198] FIG. 13 depicts a rear image of a neck array (30). Threaded on the neck array (30) is a piezo base (38) comprising openings to allow for movement along the neck array (30). Attached to the piezo base (30) is a DBM (120) as depicted in part of FIG. 12, with the difference being features (130 and 140) are exchanged for the components of the piezo base (38). The neck array (30) is a track-like structure, about which the sensor pods can slide on openings in the piezo base (38). The neck array (30) is generally C-shaped, and when the sensor pods are at the end of the track, are oriented for placement on the carotid artery. However, the sensor pods can be centrally aligned, thus being side-by-side and placed together on an area of interest.

[0199] FIG. 14 depicts a front view of the neck array (30), which more particularly depicts the piezo cap (100), the sensor pad (36), the PCB housing (115), the DBM (120), the locking cap (125). FIG. 15 provides an alternative view of FIGS. 13 and 14.

[0200] FIG. 16 depicts a variation of an array (5), having a stem (10), a left arm (6) and a right arm (7). Like the neck array (30), this embodiment of an array, comprises a pod sled (11), which allows the sensor pods (1) to move along the arms (6 and 7) or the neck (10), to allow for fit of these sensor pods (1) on a patient. A rear pod mount (12) comprises attachment means (16) which secures to the piezo cap (14). For example, the attachment means (16) may be a quarter thread, pin, and recess. Alternative is a paired threaded fastener, a set of magnets, threaded fasteners having an opening in one end and threads in the other. A piezo (13) is depicted at one end, and the sensor pad (18) can be placed on said piezo. Rotation of the rear pod mount (12) will remove the piezo cap (14) and included piezo (13). Alternatively, the pod sled (11) can be rotated in a quarter, half, or full turn to separate from the sled ball (17) and remove the entire part of the sensor pod (1) or be attached with mechanical fasteners (415). Accordingly, easy removal is possible for either just the disposable piezo component (13), or for the entirety of the sensor pod (1), by removal of the pod sled (11).

[0201] In an ideal world, every patient would be the same shape and size, and modification of the structure would not be required. However, in practice, men, women, and children have significantly different shapes and sizes due to the amount of body mass, muscle, breast tissue, fat deposits, etc. Specifically, changes in body mass and shape between the neck and the torso create issues where the array must be modified to position one or more sensors in appropriate positions for acoustic sensing.

[0202] Therefore, as used on human patients, a difficulty in such devices is that people come in all shapes and sizes and that the array must be easily modified to fit these different shapes and sizes. One option would be to utilize different sized, fixed position sensing elements, due to the fragile nature of the sensing elements. However, constant movement and replacement of the sensing elements from one device to another would likely result in more damage to the sensing elements and increase the risk for the need for frequent replacement of these elements. Therefore, an array with rails, both the neck and Y versions, provides the necessary stability and flexibility provides a great advantage in the array for use on patients.

[0203] A particular feature of the sensor pods when affixed to an array is that they are adjustable and can be configured to account for the anatomical differences between individuals while remaining sufficiently rigid to support the sensing elements. Such flexibility can be seen in the depiction of FIG. 10 or in the angled pod, in FIG. 17.

[0204] The exploded view of FIG. 17 details a variation of a sensor pod (1), showing the components that make up the sensor pod (1) able to slide along the array. The sensor pad (18) attaches to the piezo (90) via adhesives or the natural adhesion of the material. Within the piezo cap (100), receiving charging coil (400) attaches to inside of piezo cap (100) with a pressure sensitive adhesive (92). Piezo (90) attaches with pressure sensitive (92) to receiving charging coil (400). PCB contact board (105) attaches via pressure sensitive adhesive (92) to piezo (90). The receiving charging coil (400) makes electrical contact with the PCB contact board (105) with a soldered or crimped connection along wires (430). A PCB processor board (110) is then compressed adjacent into the rear pod mount (12) and makes electrical connection via spring pins (111) to PCB contact board (105). The sensor pad (18) fits within the piezo cap (100), which is attached to a pin board (400) with a pressure adhesive (92). Another adhesive connects the board to the piezo (90), and another adhesive connects this to the PCB contact board (105). A fastener (403) with a washer (405) compresses with a friction washer (407) into the knuckle (12). A sled ball (17) allows rotation of the piezo when mounted, held, in part, by the friction of the knuckle (12) and the friction washer (407). A spring (409) compresses against spring cap (410) and sled ball (17) when pod sled (11) is assembled to sled ball (17) via washers (412) and threaded fasteners (415), creating frictional pressure against the inside surface of array arm (2). This allows for very easy positioning of the pod assembly (1), anywhere along array arms without actuating any mechanical buttons. Fasteners (415) can be excluded for attachment means, such as quarter-turn, half-turn, or full-turn threaded attachment, magnetic, or other similar attachment means, to allow for easy removal of the sensor pod. Alternatively, the sensor pods can simply slide off of the end of the senor, and a new one replaced by sliding it into place. The spring (409) holds the sensor pod into place during use.

[0205] FIG. 18 depicts a cross-sectional view of FIG. 17.

[0206] FIG. 19 depicts a sensor pod having a pin mount (38). This pin mount can engage to a ball mounting system, to allow for rotation of the sensor pod. A corresponding ball recess can be provided to allow for such attachment means and rotation. The fastener acts as a ball and socket, allowing rotational movement.

[0207] FIGS. 20 and 21 depict a piezo pair that does not utilize an array. Accordingly, the piezo (150) relies upon an adhesive surface on a sensor pad (18) to allow the piezo to stick to the skin surface. In certain embodiments, it is advantageous to perform a test with one piezo at a time, with the patient laying in a position to allow for the piezo to rest with gravity. Thus, the adhesive does not need to be so strong but rather merely sufficient to hold the piezo into a relatively stable position. This may be useful for situations where an array is impracticable, whether due to the dimensions of the patient, surgical procedures, or the like, that would restrict access of an array. Furthermore, by eliminating the array, a further source of noise may be eliminated from the data sample.

[0208] FIGS. 22 and 23 depict a gel pad with cylindrical surface (600) that contacts with the piezo film (602). The upper frame (601) supports the piezo film (602) and engages with an adhesive (603) to the lower frame (604). A wiring harness (605) and solder or welds (606) connect the wiring harness to the piezo film (602). The lower frame (604) has a concave surface, and the piezo film (602) engages with this curvature resulting in a piezo having a concave surface. The concave surface allows for increased reception of both high and low frequencies, thereby increasing sensitivity in certain instances, wherein peaks may be identified at these margins.

[0209] FIG. 22 particularly depicts the cross-sectional view and side view of the film piezo (602), while FIG. 23 depicts the exploded view.

[0210] A curved film piezo can be exchanged for any of the piezos in embodiments described herein. For example, the lower frame (604) may comprise a relevant attachment means, and further comprise a PCB contact point to allow for direct exchange with prior examples and figures.

[0211] FIG. 24 depicts two different sensor pads (18) for use in an array with a piezo sensor. The sensor pads are angled at the skin facing surface, such that on the lefthand side, the curvature on the bottom right engages to an angled structure to ensure a good acoustic fit. By contrast, the sensor pad on the righthand side of the page comprises a dual concave structure, to fit around a structure that is rounded. In each case, there is a proper fit, and so the sensor pod must be able to rotate to allow the sensor to be properly fit against the skin to achieve a proper acoustic contact for data collection. Cross-sectional views of the left and right sensor pads are depicted for clarity.

[0212] The sensor pods, including both components (85) and (86), are replaced, as necessary to allow for proper functioning of the piezo sensor. These replacements are performed as necessary, but at least every 10, 25, 50, 75, 100, 150, or 200 tests. When the sensor base (86) is replaced, the disposable piezo assembly (85) is also replaced. By contrast, in each test, sensor pads (18) are replaced.

[0213] In certain preferred embodiments, the sensor pads (18) can be secured onto the piezoelectric unit via an adhesive, such as one of several common low tack adhesives for providing for a temporary securing of the sensor pad to the piezo element. Other embodiments may utilize a gel or other water or solvent based material that may secure the sensor pads without the need for an additional adhesive material. In further embodiments, the sensor pad fits into the sensor pod and secures onto the piezo without the need for any adhesive.

[0214] A particular feature of the sensor pads described in the embodiments herein is the fact that the top face shape (that contacts the patient), and the bottom face shape (that contacts the piezo) are made so that when the top face contacts the patient and thus applies pressure to the sensor pad and through to the bottom face, the piezo does not flex when pressure is applied to the sensor pad. This is important to ensure consistency and accuracy of the piezo device. Therefore, the sensor pad, in certain embodiments, is designed such that the piezo does not flex when pressure is applied to the sensor pad. In a further preferred embodiment, the piezo flexes less than about 0.1%, 0.5%, 1.0%, 5.0%, 20%, and 25% and all percentages in between. Accordingly, in certain embodiments, the amount of flex is greater than zero (i.e., rigid and does not flex), but the amount of flex is minimized to maintain accuracy of the piezoelectric unit.

[0215] It is also preferred that the sensor pads create a proper impedance matching with a patient. Accordingly, the sensor pad is designed to have a slight tackiness which ensures a proper impedance matching with the patient, which then successfully transfers sounds through to the piezo element so that the piezo can properly detect vibrations and noise signals from the patient.

[0216] Therefore, in order to maintain both sterility of the medical device and proper function of the medical device, it is necessary to provide replaceable components. The entire device is a complex system comprising a display, a base unit, an array, a sensor base, a disposable piezo assembly, and a sensor pad. Each of the last four are disposable. The array itself can be disposed of after a number of uses, likely between 100 uses and 1,000 uses. The array may lose elasticity to ensure proper fit on a patient, gain cracks, or simply lose stability. Each of these may increase variability and thus replacement is warranted.

[0217] The sensor base as depicted in FIG. 25, comprises attachment means for the sensor pod to the array, and comprises electronics for connecting the sensor itself, typically a piezo, to the device. The base, using certain elastomeric materials to allow for movement of the sensor pod, will wear with time, necessitating replacement for minimizing variability.

[0218] The disposable piezo assembly is intended for more frequent replacement than the base or the array, as the piezo is susceptible to wear or damage. Accordingly, frequent changes, such as between every use and every 10, 25, 50, or 100 uses is necessary for accurate results.

[0219] The device is a complex system comprising multiple components, each working together to ensure that accurate results are obtained. Disposable components ensure that the system works properly, every time, and that it generates accurate and reliable data.

[0220] A kit is envisioned with the system, wherein a plurality of sensor pads is provided, a plurality of disposable piezo assemblies is provided, at least two sensor base assemblies, and at least two arrays. Said kit can be used with a system comprising the base and a display, as well as necessary software and hardware for energizing and running the device through its necessary protocols.

Quality Control Methodologies and Devices

[0221] Now that we have a device that is clean and has readily replaceable components, we need to ensure that the device is properly functioning. Accordingly, we describe certain methods and embodiments that provide for self-diagnostic tests, active diagnostic tests, and guidance for properly positioning a sensor on a patient.

[0222] The quality control protocols embodiments provide for a process or method for determining if a listening device, such as a piezoelectric device, or microphone, is properly functioning. This is a self-diagnostic quality control feature. A second test is an active quality control procedure, which is performed with sensors on a patient. The two tests can be used alone, each being sufficient to confirm that the sensor is working properly, or can be used together, to both ensure proper function and also proper placement of the sensors on a patient. When performed together, the tests are performed sequentially, first the self-diagnostic test and then the active diagnostic test on the patient.

[0223] Accordingly, in preferred embodiments, methods exist for determining the proper function of the sensitive piezoelectric components. FIG. 26 depicts a first embodiment comprising an array (5) positioned over a base (300). The array (5) is but one example of a configuration of, as pictured here, three listening pods. Embodiments of sensory pods, as depicted in greater detail in FIGS. 16 and 7 depict a sensor pod attached to an array. FIG. 7, in particular, depicts a piezo sensor (90), which is the primary component that is being tested for quality control in these features.

[0224] FIG. 25 details a base (300) that provides for storage, charging, and calibration for the array (5). The base (300) comprises a base enclosure top (310), a base enclosure bottom (96), and a bottom closure plate (98). A decorative elastomeric TPE overmold (305) can be provided to protect the base (300) and the array (5). The transmit wireless charging coils (93, 94) are arranged to power the optional respective wireless charging coils of the sensor pods (1). Also arranged in the base (300) is a calibration speaker (97). The electronic module (95) powers optional transmit wireless charging coils (93, 94) when utilized with an array having a corresponding charging feature. In other embodiments, a base can directly charge several batteries or a single battery with a mechanical connection (131), as depicted in FIG. 7, as is known to a person of ordinary skill in the art. In several embodiments, the electronics module generates a calibration and verification signal to be reproduced by the calibration speaker (97). The base enclosure bottom (96) has one or more sound holes (99) arranged therein. The sound may resonate through (305), eliminating a hole through the enclosure, preventing the intrusion of cleaning liquids, dust, dirt, hair, etc. into the enclosure. The base can be secured together with fasteners, as depicted, with adhesives, plastic welding, or other similar fastening mechanisms.

[0225] In one embodiment, disposed of within the base (300) and specifically adjacent to the cradle for each of the sensor pods (1) is a respective speaker (97). A computer is coupled to the base (300) for communication via a USB connection, Bluetooth, near-field communication, RS-232, or the like. The computer couples to the speaker (97), and when the SDD (Stenosis Detection Device) is activated, a program is executed by the computer system so that it performs a diagnostic and quality control test on each of the sensor pods (1).

[0226] The diagnostic and quality control procedure comprises a program that plays a known set of sounds generally corresponding to sounds that will be detected and recorded when measuring sounds on the body of a patient. These sounds include low and high frequency sounds, typically low amplitude. Once the sounds are played, the sensor pods (1) detect the sounds and convert the sound to a digital signal that is plotted and compared to a predetermined plot of the sounds that were played. Alternatively, an analog signal is generated and compared with the predetermined plot. Each of the sensor pods (1) is independently tested to determine if it meets an acceptable standard. In one embodiment, and error message is generated if the sensor pod output is not within 10% of the predetermined plot at a given data point. Other standards can be used to determine an error condition exists. A range of 1% to 50% at each data point can be used to determine if the sensor pod (1) is not functioning properly. Alternatively, the overall plot can be analyzed, instead of a point-by-point analysis, to determine if a sensor pod (1) is functioning properly. Typically, a sensor should be within 25% of a predetermined frequency.

[0227] If any sensor pod is not detecting an appropriate sound, then the system will notify the user of an error. In most instances, the error means that a particular sensor pod has exceeded its useful lifetime and is due for replacement. These devices theoretically have a lifespan of several hundred uses under ideal conditions. However, in a medical office, the continuous placing of the array (5) on to a patient, and detecting and recording real sounds, may result in distortion after even a few uses. Accordingly, the system is able to determine whether the detected sounds are simply drift that is a slight change in the detected sounds, or whether there is an error or fault in one of the sensors. If there is only a slight drift, the system can calibrate each unit so that the measured noises from the system are consistent through use.

[0228] If the measured sounds are greater than a tolerance of more than 10%, or more than 25% as defined for the occasion, the system notifies the user through images on a display, lights on the sensor pod, audible messages, or other manner to communicate the error, and identifies which sensor pod is faulty. A user can then quickly replace the faulty sensor pod or the disposable piezo assembly (85) and rerun the quality and calibration control program.

[0229] After the sensor pod is replaced and the quality control program is rerun, and the replacement sensor pod is confirmed to be working properly, the system will alert that it is ready for placing on a patient. Each of the sensor pods can be appropriately placed onto the patient.

[0230] FIG. 16 details an embodiment of a listening device, comprising a yoke (5) having three sensing pods (1). The yoke (5) secures the three sensing pods (1), and by holding the yoke (5) at the neck (3), the sensing pods (1) can be placed against a patient's body, thereby positioning the sensor pods adjacent to the carotid arteries and the sternum. A concern arises, however, where the sensors are not in the correct location on the body, wherein a weak or improper signal is detected by the sensor pods, or when one of the sensing pods is damaged or broken in the process of moving the yoke from the base (300) to the body. This poses a challenge for the operator, as a broken sensing element would provide no signal, and wherein weak signal would not give reliable results. Furthermore, there is obvious concern for a patient, as improper or unreliable results can have significant deleterious effects. As described herein, the device, a system, and methods of use of the device and system, provide for mechanisms to assist with positioning of the device on the body.

[0231] The diagnostic and quality control procedure is depicted in a flowchart of FIG. 28. T process includes several steps as defined generally in the flowchart of steps (517)—(523). A first step (517) comprises a program that plays a known set of sounds corresponding to sounds that will be detected and recorded when measuring sounds on the body of a patient. The piezos 90 detect the audio (518), which is then converted from analog to digital (519). The digital sample is transmitted (520) to a processing unit for processing (521). A criteria challenge (522) is defined, with the criteria met (523), thus starting a patient test, or not met (524), which requires the replacement of a faulty piezo (90), through replacement of one or more components as defined herein, and restarting the test again at (517) once the piezo is replaced.

[0232] When performing the test in step (517), the sounds include low and high frequency sounds, typically at low amplitude corresponding to the range of sounds to be detected by the SDD device. Once the sounds are played, the sensor pods detect the sounds and convert the sound to digital (519). The criteria step (522) compares the digital sounds received to the actual sounds played. For example, a comparison can be made between amplitude and frequency, and overlaid to compare the two samples. Each of the sensor pods is independently determined to meet an acceptable standard, or tolerance for example within 50%. 25%, 10%, 5%, or within about 1% of the sounds based on the determined frequency and, optionally, the amplitude of the detected sounds. Simply comparison software can make these comparisons between the two sounds.

[0233] If any sensor pod is not detecting an appropriate sound, then the system will notify the user of an error. In most instances, the error means that the particular sensor pod is due for replacement. While these devices may theoretically have a lifespan of several hundred uses under perfect conditions, the reality of a medical office and placing a device on or adjacent to a patient and detecting and recording real sounds may cause distortion after even a few uses. Accordingly, the system is able to detect and determine whether the sounds detected are simply drift that is a slight change in the detected sounds, or whether there is an error or fault in one of the sensors, thus requiring replacement. If there is only a slight drift, the system can calibrate each unit so that the measured noises from the system are consistent through use. An appropriate program on the system can make these changes to the data based on the actual versus detected sounds, through a simple calibration program. Accordingly, the played tones provide for the ability to both detect and calibrate the device before every use.

[0234] If the measured sounds differ by more than the acceptable tolerance, the system engages the user through images on the display, lights on the sensor pod, audible messages, or other means for communicating error, and wherein the particular sensor pod that is faulty is identified. A user can then quickly replace the faulty sensor pod or disposable piezo assembly (85) and rerun the quality control program. An exploded view of a sensor pod is depicted in FIG. 5, wherein a portion of the components depicted therein can be appropriately placed in a single replaceable and disposable component for ease of use. This disposable piezo assembly (85) can be secured to the rest of the sensor pod via ordinary connection means such as a swivel mount, bayonet, threaded fastener, snaps, quarter-turn, magnetic, hook-and-loop, or other known attachment means.

[0235] For example, FIG. 7 as described above, depicts an outer array half (140), which connects to an inner array half (130). A PCB charger contact (131) provides for an electrical contact between a contact in the base (300) and the array. The wiring harness (132) connects to the PCB processor board in each of the attached sensor pods. So, for example, here there are depicted three sensor pods. However, in embodiments having one, two, or more than three sensor pods, fewer or additional connections would be needed. Furthermore, certain embodiments may utilize a sensor pod having multiple piezo elements. Accordingly, a wire from harness (132) will be necessary for each piezo.

[0236] FIG. 7 further depicts an exploded view of a sensor pod, with the entirety of features (90) through (125) being a complete sensor pod. By contrast feature (85) depicts a disposable piezo assembly. The disposable piezo assembly (85) comprises a piezo (90), a piezo wiring (91), which connects the piezo (90) to the PCB contact board (105). A piezo cap (100) is surrounded on each side by a pressure sensitive adhesive (92), this pressure sensitive adhesive (92) secures the piezo (90) to the piezo cap (100) and to the PCB contact board (105) on the other side with the second pressure sensitive adhesive (92). These components can be normally configured in a disposable arrangement, wherein the quarter turn locking feature (101) can be used to screw on and off the disposable (85) by connection to the quarter turn locking pin (116). The quarter-turn feature can be exchanged for other locking or attaching features, such as magnetic attachment, compressions/friction, one or more threaded fasteners, and the like. Known attachment means are known to a person of ordinary skill in the art.

[0237] When the disposable piezo assembly (85) is attached, it contacts the PCB processor board (110), which assembles into a pocket in (115), and is captured by (85). In this manner, when a quality control test is performed, and a sensor is identified as faulty, the attachment means can be withdrawn, and the disposable piezo assembly (85) can be removed and a new disposable piezo assembly (85) attached and the test rerun.

[0238] Iii certain embodiments, it is advantageous to have the entire sensor pod replaced, not just the top disposable component. For example, the PCB hoard (110) may in some instances wear or be damaged. Alternatively, the diaphragm bellows membrane (120) may need replacement, or simply replacement is warranted because of contamination concerns. Accordingly, the entire piezo assembly can be replaced, by removing threaded fasteners (133) or by removing locking cap (125).

[0239] The diaphragm bellows membrane (120) locks with certain features, to ensure that it can freely flex and compress to allow for the fit of the piezo against the body. The diaphragm bellows membrane (120) fits feature (121) into a locking groove (117), which traps locking feature (121) between locking cap (125) and the PCB housing (115). Locking feature (122) secures the diaphragm bellows membrane (120) between the inner array halve (130) and the outer array halve (140). This creates a flexible “drumhead.”

[0240] For each use of the piezo, a sensor pad (18) is also utilized for sanitary conditions and to ensure a quality sound contact to the piezo (90). The sensor pod (1) of FIG. 3 can be replaced by sliding off the track or removing the track base (11), and replacement by sliding on a new pod, or attaching the new pod over the track.

[0241] After either replacement of the disposable component (85) or replacement of the entire sensor pod, the quality control program is rerun and the replacement sensor pod is confirmed to be working properly, the system will alert that it is ready for placing on a patient. Each of the sensor pods can be appropriately placed onto the patient, as depicted in FIG. 10.

[0242] As depicted in FIG. 11, when the carotid artery is tested, at least one sensor pod is placed adjacent to either the left or right carotid artery. Optionally, a sensor can be placed adjacent to the heart. The sensor pads (18) are placed on the skin of the patient at the carotids. In certain embodiments, the heart sensor, if utilized, can be placed over the clothes of a patient, as it is detecting heart rate, which is sufficiently loud to not need to be directly on the skin. However, for more precise applications, a skin-to-skin application is needed. Indeed, in certain embodiments, a sensor array comprises only one or only two sensor pods, and no pod is placed adjacent to the heart.

[0243] As with the qualify control procedure on the base unit, once the sensor pods are placed on the patient, the operator can engage the device to begin detection and recording on the patient. Because the sounds that are being detected and recorded are known within a certain range of sounds, that is, the sounds are generally known to a certain frequency and amplitude, and a further quality control test is performed for a duration of between 1 second and 30 seconds. This test provides a quality control diagnostic to ensure that the sensor pods are detecting proper sounds from the patient, and thus confirms two pieces of information: first the proper placement of the sensor pods on the patient; and second that the sensor has not failed in the time between initial quality control tests and placement on the patient.

[0244] Since there are at least two and likely three sensor pods, each pod communicates with the computer identifying the detected sounds, which can be recorded by the system and compared in real time to a predicted sound. Accordingly, the sensor pod at the heart will predict a certain sound and the sensor pod(s) at the carotid arteries another sound. If one or more sensors does not detect the predicted sounds, a signal will engage to identify the sensor that is not properly detecting the predicted sound. This signal will alert the operator that the sensor pod needs to be adjusted to a different position to properly detect the sounds for the particular test.

[0245] FIG. 31 provides a representative flow chart of an embodiment of this active quality control process. First, the sensor is placed on the patient (510). The piezos then start receiving sounds from the patient (511). The received sounds are then compared to expected sounds from the patient (51?). The comparison identifies an expected frequency at each piezo. For example, we expect to hear the heartbeat at about 1 Hz. Accordingly, if this sound is received by the piezos, within 25%, 10%, 5%, or 1% of the expected frequency, then we know that the devices are properly positioned over the carotid arteries. Alternatively, we can look for a frequency between 60 Hz and 260 Hz, which corresponds to the large ring vortices at the carotid artery. This corresponds to the expected stenosis at the carotid artery. Intensity is patient relative. Accordingly, when intensity is utilized as a parameter, an expected value may be assumed, but the system can simply identify relative intensity that is by repositioning a sensor, the intensity may be increased or decreased from the prior position, with an increase in intensity being an improved position. Accordingly, an indicator on a display, volume of sound being played through the speaker, rate of flashing of a light on the sensor, sensor array, or the base, or a set of indicator lights, with more lights showing greater intensity and fewer lights showing lower intensity. Those of skill in the art will recognize there are numerous ways to indicate a change of intensity.

[0246] If the criteria are met (513), then we proceed to start recording the data and processing the patient (516). However, if the criteria are not met, we need to first adjust the piezo on the patient (514). Adjustments can be just a few centimeters, or more as necessary, in order to get the piezo closer to the artery of interest. After adjustment, the device again receives sounds from the patient (511) and compares the sounds to the expected sounds (512) to determine if the criteria are met.

[0247] In certain instances, after movement and adjustment of the device, the piezo is still not finding the proper sounds. This can be due to continued improper placement or failure. Accordingly, it is best to replace the piezo (515) and start another quality control procedure as outlined above on the base.

[0248] The embodiments of the system utilize variations of quality control programs for initial setup testing of the sensor pods and then for quality control testing of the proper position on the patient. A variety of alarms, indicators, or signals can be utilized in each of the quality control programs to ensure that the issue is detected and corrected.

[0249] For the initial quality control program, when the sensor pods are still in the base unit cradle, it is appropriate to indicate a fault with a computer graphical user interface (GUI) as depicted in FIG. 29. An image of the specific array and number of sensor pods is indicated on a screen. The system can recognize the number of sensors based on data received and will indicate proper function or improper function of each. For example, the GUI may indicate with a green color at each sensor that it is functioning properly, or a red light when improperly functioning and requiring replacement. Alternatively, an arrow or words may indicate replacement or proper function for each sensor. Instructions to replace a sensor will be indicated on the screen with step-by-step directions based on the particular type of connection mechanism. After replacement, the quality control program can be rerun to confirm proper function.

[0250] In other embodiments, a colored light system, such as a green or red light based on green being good, and red signaling an error with the sensor pod can be directly placed on the sensor pods (see FIG. 27). Indeed, FIG. 27 depicts a first indicator light (61) and a second indicator light (62) illuminating through a clear TPE overmold material (60). These can be illuminated based on the pass or fail of a particular process. A third or additional lights are depicted, but not labelled, and can be further utilized as described herein.

[0251] FIG. 30 depicts a plurality of lights will indicate based on the self-diagnostic phase of the test. Color changing LED lights, or simply alternating LED lights, or an equivalent, can be used to provide easy indication with different colored lights, shown through clear or translucent plastic housing. These lights can be placed on the base unit itself. In other embodiments, or in addition to these lighting systems, an audible alarm may signal from the SDD device to warm of an error. Furthermore, the display unit may further provide for a display indicating which of the sensor pods needs to be replaced.

[0252] The lights of FIG. 27 and FIG. 30 can also be used during the active diagnostic phase. For example, a set of three lights can be used, green indicating proper sounds received and proper placement and red for improper placement or failure, i.e., not meeting one or both criteria. However, a yellow light may be further included for several reasons. First, the yellow light may hold steady or flash to indicate that the self-diagnostic or active diagnostic phase is being performed. The yellow light may stay illuminated, or joined with a green or with a red, if, for example one of the criteria are not met. This would indicate that the sensor is functioning but that it is improperly placed. For example, the intensity is not sufficient, or the frequency improper, would suggest that the device is not in the proper locating for high quality data. The device can be adjusted on the patient and the active diagnostic phase continues until either a green light is indicated for all sensors or a single red light is indicated on one sensor.

[0253] In certain embodiments, a button on the device or on the base is pressed to perform the active diagnostic phase. However, in preferred embodiments, once the self-diagnostic test is complete, the active diagnostic phase immediately starts. The active diagnostic phase will continue, until either all sensors indicate green or one indicates red. Typically, this will last up to 30 seconds, at which time a red light will indicate to restart the test, or to replace a sensor.

[0254] If one sensor remains yellow or yellow with green/red, during the active diagnostic step, the lights, visual, and or audible alarms can further assist in positioning the device properly on a patient. For example, the light remaining yellow will turn to yellow and green, if the signal is better, or from yellow to yellow and red, if the signal is worse. Accordingly, the sensor can be moved in a proper direction toward the yellow/green until just a green light is indicated. Furthermore, the GUI can be utilized in the same manner, with an indicator on the screen suggesting the direction to move the sensor. Ultimately, if a sensor pod does not detect the proper sounds from the patient, then one or more alarms will register, and the operator will know that one or more sensor pods need to be replaced on the patient. In certain embodiments, the visual screen, a visual identifier will flash to aid the operator in placing the sensor pod in the proper location.

[0255] In further embodiments, where a sensor pod is identifying an improper sound or not detecting a sound, a visual alarm may be generated, such as a red light, which indicates improper position or a sensor failure. The SDD can detect and compare the sounds in real time, so the operator can then slowly move the sensor pod to a different location and wait a few seconds to see if the light turns from red to green, indicating a proper position. The operator can continue to move the sensor pod on the patient until it is indicated on either the sensor pod, on the array, or on the SDD device display that the position is correct.

[0256] If the operator is unable to determine a proper location on the patient after 30 seconds, the SDD will alarm with a visual or audio signal to perform a base unit quality control procedure again to ensure that the sensor pods are all functioning correctly, or to simply replace the sensor that indicated failure. After replacement or if the sensor pods are determined to be functioning correctly, the operator can again restart the process of placing the sensor pods on the patient.

[0257] Accordingly, a preferred embodiment for determining proper placement of sensor pods on a patient comprises a stenosis detection system comprising a base unit having a cradle, at least two sensor pods, a display and at least one alarm mechanism; wherein while the sensor pods are engaged in the base unit cradle a self-diagnostic quality control procedure is performed to confirm that the sensor pods are properly functioning. After confirmation of the proper function of each of the sensor pods, the devices can be placed onto a patient wherein an active quality control procedure is performed. The active quality control program is run for between 1 second and 30 seconds wherein each sensor pod is communicating with the compute of the detection system in real time to ensure that each of the sensor pods is measuring the appropriate sounds. Wherein the system provides for an audio or visual notification that the active quality control program is met, or wherein the system identifies one or more sensor pods that are improperly placed. Wherein the system then provides an alarm to any sensor pod that is not properly placed. Wherein a visual or audio mechanism is provided to provide real-time feedback as to the proper position for each sensor pod, and wherein one example provides for a red light for improper position and green light for a proper position. Certain embodiments utilize a yellow light to indicate that one or more of the self-diagnostic test or active diagnostic test are proceeding.

[0258] Other audio or visual alarms or mechanism may be further included in the system so as to aid in the placement of the sensor pods on a patient.

[0259] In preferred embodiments, the active quality control step on the patient provides for immediate real-time feedback to the correct placement of each sensor pod to ensure fast and reliable positioning of the sensor pods and also to confirm fast, precise, and accurate detection and determination of stenosis on the patient.

[0260] The method comprises: performing a first base unit quality control test; confirming that each of the sensor pods is properly functioning; placing sensor pods on a patient; performing a second quality control test, wherein the sensor pods detect sound in real time and compare said sound to a predicted sound; and indicating with an alarm whether the sensor pod is properly placed on the patient by comparing the detected sound in real time to a predicted sound based on historical data.

[0261] In a preferred embodiment the system uses a computer to run software to implement the features as described in the embodiments herein. Accordingly, the computer is connected to the array and/or to the sensor pods via a connection means either wired or wireless, as is known to one of ordinary skill in the art. The software comprises the various quality control procedures, as well as appropriate code to provide alarms and to notify of the need for replacement or modification. Further features include the ability to calibrate the system in view of a quality control test.

[0262] Therefore, preferred embodiments of the disclosure comprise a method of confirming the proper position of a medical device upon a patient comprising: performing a first quality control procedure to ensure functioning of the sensor pods, comprising playing a predetermined set of sounds and comparing the predetermined sounds to the detected sounds; performing a second quality control procedure while detecting sounds from a patient wherein the test compares the detected sounds to sounds that are ordinarily present in detection of the particular artery or vessel of interest; and triggering an alarm wherein the detected sound does not meet the predicted sound, or triggering an approval if the detected sound confirms with the predicted sound.

Noise Attenuating Strategies

[0263] A major hurdle in creating a device that conforms to the necessary levels of accuracy is to ensure that the data received for each test is of the highest quality. By performing the prior quality control procedures, the devices are known to be functioning properly. However, it is necessary to now utilize passive and active noise attenuating strategies, as well as computer implemented denoising strategies to generate clean and clear data. Accordingly, we need to eliminate noise from the data sample in any number of ways, so that the resulting data is clean and clear for quantification of stenosis.

[0264] The noises that we are particularly measuring are subtle large ring vortexes. These vortexes are created as wall pressure fluctuations distal to a constriction (stenosis) in rigid or elastic pipes, or in arteries, reveal the presence of low-frequency maxima. These fluctuations are found to be associated with large-scale, medium-scale, or small-scale vortices (also called “eddies” if small), that are strong in the region distal to the constriction (called “stenosis” when in an artery).

[0265] Normal blood flow in a heathy patient causes certain sounds which are detectable by our device. Patients which have stenosis in the carotid arteries will often have another 2 or 3 additional sounds that can be picked up by our device. Depending on the amount of stenosis and how many stenosed areas the sound will change. The carotid artery has a branch which feeds two main areas in the head. One main branch going to the brain and the other branch going to the face. The area that we test for is where the carotid artery branches into these two areas. Thus, depending on if there is stenosis in one branch or two can lead to multiple sounds being picked up. Because these sounds/vibrations are at such a low level it is vital to make sure as much external noise is eliminated as possible. Even small noises in the 20 Hz-3,000 Hz range can overwhelm the noises we are looking for making noise elimination critical.

[0266] With regard to flow and the noises created therein, some of the fluid flow energy enters into the vortex motions distal to a constriction, which then results in an increase in the wall pressure amplitude, above that of turbulence alone, at the lower frequency end of the wall pressure power spectrum. These maxima are nearly Gaussian-shaped bell curves situated atop a broad, nearly flat spectrum at low frequencies that is due to turbulence within the pipe or artery. The maxima are always found at lower frequencies than the so-called “break” frequency characteristic of the turbulence spectrum where the latter changes quite abruptly from nearly flat to steep declining in intensity (when the logarithm of signal intensity is plotted versus a logarithmic frequency scale).

[0267] Interestingly, measuring these maxima and plotting the power spectrum provides for a visual image of stenosis in an artery. Indeed, we have determined that by plotting the power spectrum on the y-axis and amplitude on the x-axis, we can effectively determine the percentage of stenosis in the carotid arteries of a patient.

[0268] These maxima (generally two in number) are the main features in the frequency power spectrum at low frequencies generated by the wall pressure fluctuations when there is a constriction as compared to the situation of no constriction yet fully developed turbulence. In order to analyze this data, we have developed devices and invented several methodologies and processes that reduce or eliminate extraneous noise from the data samples, to enable further spectrum analysis downfield.

[0269] The device eliminates noise in several ways. One by using sound barriers/dampening material to eliminate external noise as much as possible as well as noise caused by the patient moving, i.e., passive noise canceling. We also eliminate or cancel ambient noise with active noise canceling strategies, whether generating opposing waves or subtracting ambient noise; finally, we denoise the received data by methodologies related to data processing using Wavelet, Welch's method, and Burg's Method. Ultimately, we plot peaks on a PSD and calculate stenosis of an area of interest in the arterial circulatory system through comparing these peaks on the PSD.

Passive Noise Canceling Strategies and Methodologies

[0270] A first set of strategies includes mechanical strategies to eliminate or reduce noise. We can also consider these strategies to be passive noise canceling strategies.

[0271] For example, in preferred embodiments, the yoke (5), as depicted in FIG. 5D is made of a plastic or a polymer. Construction of a yoke with as few components as possible is intended, as additional components create joints that may cause ambient noise to the system. We typically use unibody constructed devices, molded into a form, or devices having an inner and outer portion, thereby allowing some materials to be compressed within said device, and for insertion of wires, batteries, processors, memory, and the like, into the array. In embodiments where multibody construction is used, it is preferable that mechanisms are in place to ensure proper stability and to prevent unnecessary vibrations and sound due to the construction. This can be achieved through appropriate materials and fixing mechanisms, including the use of dampening materials when connecting two or more components together on the yoke (1). The yoke (5) may further optionally include sound canceling materials disposed of in or on the yoke (5). This provides that movement of the yoke (5) or of the patient while the yoke (5) is on the patient, will prevent unnecessary noises that may disrupt the sound received by the piezos.

[0272] FIGS. 24 and 32 depict disposable sensor pads (18). These pads (18) serve as the first line of active noise canceling, where the pads (18) have a durometer and shape to allow for secure contact with the skin of a patient, which blocks some ambient noise from entry to the piezo sensor (90). The sensor pad (18) is placed on the piezo (90) and positioned such that a flat side of the pad is in contact with the piezo (90) and the obverse side is in contact with the skin of the patient. Particular designs, such as those in FIG. 24 are angled on the skin facing side to create a good seal against the skin. The sensor pads are angled at the skin facing surface, such that on the lefthand side, the curvature on the bottom right engages to an angled structure to ensure a good acoustic fit. By contrast, the sensor pad on the righthand side of the page comprises a dual concave structure, to fit around a structure that is rounded. In each case, there is a proper fit, and so the sensor pod must be able to rotate to allow the sensor to be properly fit against the skin to achieve a proper acoustic contact for data collection. Cross-sectional views of the left and right sensor pads are depicted for clarity. The sensor pads (18) further direct sound and vibrations from the patient's skin to the piezo and results in sound and data that eliminates some noise from the signal.

[0273] In further embodiments, it is advantageous to utilize gel on the skin of a patient that assists in forming a temporary seal between the pad and the skin of the patient. Certain oil- and water-based gels or liquids are useful in assisting with the seal.

[0274] FIG. 32 adds a further feature, which is an external noise attenuating material (219) that compresses around the sensor pad (18). The external noise attenuating material (219) is like an “over-the-ear” headphone, which blocks ambient noise from the ear. In the similar manner, the external noise attenuating material (219) surrounds the sensor pad (18) and blocks some of the ambient noise.

[0275] The sensor pod itself, therefore, must also attenuate and block out some of the ambient noise. This can be achieved through several features that are depicted in detail above in FIG. 8B, however it is again relevant for our purposes here. FIG. 8B depicts an exploded view of a sensor pod, beginning with the piezo (90) which is attached to the sensor cap (100) with an adhesive (92). The piezo (90) fits within a recess at the top of the sensor or piezo cap (100) and sits on a flange on the opening in piezo cap (100). The piezo cap (100) is made of a plastic material having a density to attenuate and reduce penetration of sound waves. Accordingly, sound will travel from a sensor pad (18) placed onto the top surface of the piezo (90) but will be limited from the bottom surface or from the side of the piezo, due to the construction of the sensor cap (100) and the remaining components. Higher density materials have greater sound attenuating properties, so appropriate density plastics can be selected around the piezo (90) to reduce ambient noises.

[0276] A second adhesive (92) connects to the printed circuit board (105), and several PCB contacts (106) contact the spring pins (111) on the PCB processor board (110) to make electronic connections. A processing unit (112) is defined on the bottom of the PCB processor board and comprises a battery, memory, and a processor. Alternatively, a battery may be centrally located, and the processing unit may be centrally located. The piezo cap (100) contains a groove (101) to receive a quarter-turn locking feature (116) that is located on the PCB housing (115). This housing, like the PCB cap (100) attenuates and reduces ambient noise penetration to the piezo (90). A screw (113) secures the PCB housing (115) to a diaphragm bellows membrane (120), which allows movement of the entire sensor pod in directions in the lateral and longitudinal axis. Accordingly, when a device is placed against a surface, the sensor pod will be able to move away from the surface, or laterally to create a better fit toward the skin of the patient. Furthermore, this diaphragm bellows membrane (120), being nonrigid, will reduce the transfer of vibration and movement from a person holding a device containing the sensor pod, such as an array. A locking mechanism (121) secures the inner portion of the diaphragm bellows membrane (120) between the locking groove (117) and the locking cap (125).

[0277] Accordingly, an embodiment of the disclosure comprises passive noise cancellation strategies comprising a sensor pod (features [85] and [86] together) comprising a disposable piezo cap (85), having a piezo (90), a piezo cap (100) having noise attenuating properties, and a PCB house assembly (86) having a PCB board (110), a diaphragm bellows membrane (120), and a PCB housing (115). A locking feature on the PCB housing (115) connects to the piezo cap (100) to secure them together. The rear of the PCB house assembly (86) comprises a diaphragm bellows membrane (120) that allows for movement of the components to isolate them from ambient noise and vibrations. The device may further comprise a noise attenuating material (219) disposed of around the sensor pad (18) to passively waves from the piezo sensor (90).

[0278] FIG. 35 further details a sample piezo utilizing sound attenuating materials. The sensor pad (18) is positioned on the sensor (13), with attenuating materials (661, 662, 663, 664, 665, 666, 667, and 668) surrounding the sensor (13). By use of these materials, we can surround the sensor (13) with attenuating materials and reduce the ambient noise that is received at the sensor. Appropriate low- and high-density materials can be use, sound baffling materials and the like.

Active Noise Canceling Strategies and Methodologies

[0279] In addition to the passive noise canceling features of the sensor pod assembly, a further strategy for reducing noise to the piezo includes active cancellation of noise, such as found in the frequency chart of FIG. 39. Active noise cancellation can be produced through several different strategies. A first strategy utilizes a second microphone or piezoelectric device to measure ambient noise. For example, in FIGS. 34A-34E, different variations of this strategy are provided. An overview of these strategies is depicted in flow charts of FIGS. 33A, 33B, and 33C

[0280] FIG. 33A depicts an electronic diagram depicting a signal received (330), ambient noise (331), and a subtraction (332), wherein the ambient noise (331) is literally removed from the received signal (330) to generate the subtracted signal (332). FIG. 33B provides a further flowchart of this concept. For example, box (340) defines reading the analog sounds from the ambient room, converting these to digital (342), converting to a frequency domain (343). In parallel, the analog signals are received from the carotid artery (341) or another artery of the circulatory system, converted to digital (342), converted to frequency domain (343), and then the ambient room sounds are subtracted from the sounds from the artery (344). The different in sound is then converted back to time domain (345), and the data is processed (346) to calculate occlusion or stenosis of the artery being reviewed.

[0281] FIG. 36 depicts an active cancellation flow chart. A sensor reads analog sounds from and ambient room (351). Parallel sensor reads analog sounds from the carotid artery (350). Each sound is amplified to a desired volume in (352). Signal from the ambient room (351) is phase shifted 180° (353), and the phase shifted sound (353) is emitted (354). Sounds are received by a microphone (355) and converted to digital signals. This effectively removes the ambient sound (351) from the digital signal processed from the carotid (350).

[0282] FIG. 37 depicts a chart using wireless modules as features (350A)-(350C), (351A)-(351C), (352A)-(352C), and (355A)-(355C). Wireless transmission (365) sends signals to the computer (354).

[0283] FIG. 34A depicts a paired piezoelectric device, having a first piezo (90) and a board (110) positioned between the first piezo (90) and a second piezo (150). The first piezo (90) would engage to a disposable pad (18) and be placed against the skin of the patient. The sounds from the patient would be detected through the disposable pad (18) and by the first piezo (90). The first piezo (90) would also pick up ambient noise, as well as noise and harmonics from power lines, in the 60 Hz frequency. The purpose of the second piezo (150) is to detect these same ambient noises as the first piezo (90) but to not detect (or to detect at a much lower intensity) the sounds from the arterial circulatory system being investigated. The sounds from the second piezo (150) can then be compared to the sounds from the first piezo (90) to identify and eliminate background sounds from those from the arterial circulatory system. The subtraction process is depicted in flowcharts of FIGS. 33A-33C.

[0284] FIG. 8A depicts a further exploded view of FIG. 34A and includes additional components. The piezo (90) engages to the piezo cap (100) with an adhesive (92) on a flange in the piezo cap (100). An adhesive (92) attaches the PCB contact board to the PCB board (110). Below the PCB board, is a second piezo (150), with is attached to the PCB board with a wiring harness (91). Both piezos can be contacted with a PCB board (105) and contact pins, as depicted in FIG. 8A. The second piezo (150), being isolated by the PCB board (110), then detects ambient sounds and not the sounds from the patient.

[0285] Cancellation and subtraction of sound can be accomplished in two ways. First, the sounds from the second piezo can be inversed and literally subtracted from the first piezo. Second, the sounds can be eliminated in analog by sending in a negative background signal which eliminates the sound. The prior art details several noise canceling headphones, which use an external microphone to detect sound. This sound is then processed by a computing system with the device, and identifies and generates an out of phase sound, being out of phase by 180°. This, when combined with the external sound, effectively cancels out the sounds that are received. Either method is functional, though the subtraction method may be preferable in certain embodiments.

[0286] FIGS. 34B, 34C, 34D, and 34E each detail a slightly different strategy for identifying ambient sounds for active cancellation. For example, FIG. 34B depicts a parallel piezo setup, comprising a base chip (26) and a first piezo (24) and a second piezo (25), arranged in parallel. This setup will allow for detection of stenosis along a linear path and determining of position of an occlusion between the two piezo sensors. This occurs as each piezo will detect the same sounds but receive them at slightly different times. This allows for positional identification of the underlying blockage. Furthermore, one piezo may be contacted with the sensor pad (18) and a second not, thus allowing for subtraction strategies.

[0287] FIG. 34B depicts an array (5) comprising three sensor pods (1) and a microphone (27) on the body of the array. In this manner, the microphone (27) can pick up ambient sounds but will be separated from the sounds of the arterial circulatory system that is being investigated. The microphone (27) can be any ordinary microphone or can be a copy of the piezo that is each of the sensor pods (1) so that the sounds can be closely matched.

[0288] FIG. 34D depicts a microphone or piezo (28) depicted on a base (300). FIG. 34E depicts a microphone (30) or piezo on a cart (32) device.

[0289] A particular method comprises a method of reducing noise to a sensor comprising: engaging a first sensor to a patient and a second sensor to ambient air, adjacent to said first sensor; detecting noises from said patient and simultaneously detecting noises from ambient air with said second sensor; subtracting the noise from said second sensor from the data from said first sensor, which will remove the ambient noise from the data from the first sensor.

[0290] A particular method utilizes a phase change detected from a sensor to modify the sounds received at an adjacent sensor; a first sensor placed on a patient to detect sounds from the patient; a second sensor placed adjacent to said first sensor but shielded from the sounds of the patient; performing a phase change on the sounds received in said second sensor and emitting a proportional sound in said phase change.

Analysis-Based Noise Filtration Methods

[0291] Active and passive cancellation can provide for a dramatic reduction in the amount of noise that ends up in a set of collected data. However, even with these background strategies to reduce and eliminate noise, detection of low frequency sounds can often be understood as looking at sounds that are “in the weeds.” Accordingly, further processing may be necessary, in certain embodiments, to collect data, amplify the data and perform certain analysis using a computer to clarify the data for best analysis.

[0292] Spectrum analysis, also referred to as frequency domain analysis or power spectral density (“PSD”) estimation, is the technical process of decomposing a complex signal into simpler parts. As described above, many physical processes are best described as a sum of many individual frequency components. Any process that quantifies the various amounts (e.g., amplitudes, powers, intensities, or phases), versus frequency can be called spectrum analysis.

[0293] Spectrum analysis can be performed on the entire signal. Alternatively, a signal can be broken into short segments (sometimes called frames), and spectrum analysis may be applied to these individual segments. Periodic functions (such as sin(t) are particularly well suited for this subdivision when t (time) includes several cycles. General mathematical techniques for analyzing nonperiodic functions fall into the category of Fourier analysis.

[0294] The Fourier transform of a function produces a frequency spectrum which contains all of the information about the original signal, but in a different form. This means that the original function can be completely reconstructed (synthesized) by an inverse Fourier transform. For perfect reconstruction, the spectrum analyzer must preserve both the amplitude and phase of each frequency component. These two pieces of information can be represented as a two-dimensional vector, as a complex number, or as magnitude (amplitude) and phase in polar coordinates (i.e., as a phasor). A common technique in signal processing is to consider the squared amplitude, or power. In this case the resulting plot is referred to as a power spectrum.

[0295] In practice, nearly all software and electronic devices that generate frequency spectra apply a Fast Fourier Transform (“FFT”), which is a specific mathematical approximation to the full integral solution. Formally stated, the FFT is a method for computing the discrete Fourier transform of a sampled signal.

[0296] Because of reversibility, the FFT is called a representation of the function, in terms of frequency instead of time; thus, it is a frequency domain representation. Linear operations that could be performed in the time domain have counterparts that can often be performed more easily in the frequency domain. Frequency analysis also simplifies the understanding and interpretation of the effects of various time-domain operations, both linear and nonlinear. For instance, only nonlinear or time-variant operations can create new frequencies in the frequency spectrum.

[0297] The Fourier transform of a stochastic (random) waveform (noise) is also random. Some kind of averaging is required in order to create a clear picture of the underlying frequency content (frequency distribution). Typically, the data is divided into time segments of a chosen duration, where time is long enough to include several cycles of typical frequencies, and transforms are performed on each one. Then the magnitude or (usually) squared-magnitude components of the transforms are summed into an average transform. This is a very common operation performed on digitally sampled time-domain data, using the discrete Fourier transform. This type of processing is called Welch's method or Entropy Maximum (Burg) method. These methods are known and understood by a person of ordinary skill in the art. When the result is flat, it is commonly referred to as white noise. However, such processing techniques often reveal spectral content even among data which appear noisy in the time domain.

[0298] Accordingly, by taking a piezoelectric unit, capable of measuring sounds and vibrations at low amplitude and within a particular frequency range, we can measure the wall pressure fluctuations due to stenosis. Accordingly, the sensitive piezoelectric devices combined with amplifiers are placed onto the skin above the carotid artery and the piezoelectric device detects these sounds. The detected sounds are then passed through analog to digital converters before reaching a computer in which further amplification and an analysis of the signal occurs.

[0299] In the case of the arterial circulatory system, the piezo is placed on the skin above the artery in the region of a suspected stenosis. In the case of a carotid artery the placement would be on the neck, slightly below the ear. The particular placement of the piezo and the location of the stenosis is suggested by Fredberg and Borisyuk. Indeed, in an artery, between the stenosis and the region where turbulence has significantly decayed, the intensities can be rather large, where the wall can be subjected to large fluctuating stresses imposed by the turbulent blood flow. [Fredberg 1974] The distance over which this occurs is estimated to be about 12D downstream, where D is the normal diameter of the carotid artery. [Borisyuk 2010] For a typical internal carotid D of 0.5 cm, that distance would be of the order of several centimeters.

[0300] Detection of vortices generated due to flow in the carotid artery produce low intensity sounds that are related to development of stenosis in an artery. These low intensity sounds are sometimes difficult to detect and to pull out of the mass of noise being generated by the body. Accordingly, a highly specialized detection device using piezo devices for arteries that are near the surface. In the relevant frequency range of 20 Hz to about 3,000 Hz, the wavelengths are long compared to other lengths, such as artery length or thickness of tissue between the artery and the skin. In this case the surface is still within the “near field” of a wave (much closer than one wavelength), in which case the tissue acts as an incompressible medium. The energy in the near field of a wave is attached to the source and cannot propagate away. Thus, there is no net energy flux out from the source. Because near-field pressure fluctuations cannot propagate away, they are generally called “pseudo-sound.”

[0301] Borisyuk [2010] has been able to relate the shape of the power spectrum at the surface to the vortex structures in the blood flow distal to a constriction. He divides the region distal to a constriction into three: Region I. The flow separation region, in which a jet flow of higher velocity, in the center, acts separately from the slower flow outside the jet. Region II. The flow reattachment region. The two regions, Region I and Region II, constitute the “most disturbed flow region.” The length of the first two regions, Region I plus Region II, based upon extensive calculations, Borisyuk estimates to be less than 7D, where D is the normal diameter of the artery. Here, stenosis may be detected in several different arteries in the arterial circulatory system. For example, detection may be directed toward detecting stenosis in the Internal Carotid Artery (ICA) in an adult, in which D is approximately 0.7 cm but the internal carotid is typically 0.5 cm. Therefore, the total length of the regions spoken of, Region I and Region II, would be at most about 3.5 cm. Region III is the region of flow stabilization where flow develops into the less turbulent flow farther upstream. This region extends from at most, 7D to 12D, or in the case of the ICA, at most from about 3.5 cm to about 6 cm.

[00002]$v={V\left(\frac{D}{d}\right)}^2.$

[0302] Conservation of fluid requires that Let lower case v be the flow velocity inside the constriction and capital V the flow velocity past the constriction. Let d be the diameter of the flow inside the constriction. Borisyuk suggests estimates of two characteristic ring vortex frequencies. The first, f.sub.1, of vortices inside the jet, with typical size d; the second, f.sub.2, of vortices between the jet and the outer wall, with typical size, D.

[0303] Accordingly, Borisyuk provides for a broad disclosure that certain structures in the blood generate flow patterns. Based on these flow patterns, and separated into three regions, Borisyuk estimates characteristics of vortex frequencies. However, these estimations provide only a rough estimate as to a vortex structure.

[0304] Accordingly, our method for determining stenosis consists in connecting the frequencies associated with largest intensities in the spectral domain to three frequencies, f.sub.1 through f.sub.2, in order to obtain estimates of percentage stenosis of the artery,

[00003]$\left(1-\frac{d}{D}\right)\times 100.$

[0305] The method has been implemented in a computer language we convert to binary, encrypted to be packaged as one whole product, software and hardware. The particular software used to run the data analysis can be determined by a person of ordinary skill in the art.

[0306] A particular embodiment comprises the following steps: A sensor device is placed on a patient and data is sampled from the patient and the sound/vibrations are converted from analog to digital. The data is streamed from the device with both of the sensors in one data stream. We break the data stream down into two streams, one for the left sensor and one for the right. We then begin the Wavelet analysis which takes out noise. After the Wavelet removes the noise a power spectral density analysis is done, and we are given a power spectral density (PSD). This tells us what frequency noise is found within the data and how strong/powerful the noise is. Because the PSD gives transient noise smoothing the PSD must be done to correctly identify the strongest peaks within the data. After smoothing is done peaks are determined and based on the where the peaks are will determine the amount of stenosis or whether no stenosis is present. If there is one peak, no stenosis is present. If there are two or more peaks the patient has some stenosis present.

[0307] Wavelets have been frequently used in digital signal processing and are often known as small waves. A wavelet is a real-valued integral function ψ: R.fwdarw.R satisfying Zψ(t) dt=0. For practical applications, it has n vanishing moments: Z t pψ(t) dt=0, p=0, 1, . . . , n−1. Consider the following family of dilations and translations of the wavelet function ψ defined by ψjk(t)=2−j/2ψ(2−j t−k), j, k=0, ±1, ±2. The terms j and 2j are called the octave and the scale, respectively. By construction, this family consists of orthogonal basis functions in the sense that for a given time series or observed signal or simply data y(t), it can be written as the sum of these basis functions in a unique way: y(t)=X j X k djkψjk(t), where djk is the discrete wavelet transform (DWT) of y(t) given by djk=Z y(t)ψjk(t) dt, j, k=0, ±1, ±2. In practice, data is decomposed into its rough approximation at the chosen resolution level J (signal of interest) and details on a finite number of resolution levels j(≤J). The latter will be considered as noise. Denoising is equivalent to removing the details to allow for improved fit and prediction of peaks in a PSD plot.

An Example of the Process for Calculation

[0308] FIG. 38 details a flowchart of the process for denoising a sample after the passive and active noise cancellation steps. A first step is to read in data and separate it into different channels (70) based upon the number of piezo sensors. A single sensor will have only one channel, two sensors two channels, and three, as in FIG. 38, three channels, etc.

[0309] We next perform a wavelet analysis (71) to denoise the data by removing low-frequency components 1 Hz-60 Hz or 1 Hz-70 Hz. After the wavelet analysis we generate a power spectral density (PSD) (73) using the denoised data, in combination with Welch's method and/or Burg's Method. From this PSD plot, we detect a first spike, typically between 75 Hz-250 Hz (74), though it can go as low as 60 Hz. Where lower peaks are present, the Wavelet is rerun to remove a lower set of data, so that the first peak is not obfuscated.

[0310] If a first spike is present between 75 Hz and 250 Hz, we continue data acquisition (74). In certain embodiments, if there is no spike in this range, the sensor is adjusted (72) and the data acquisition process is restarted. Using this embodiment, we effectively build in a mechanism to ensure proper placement of the sensor, to make sure we have good quality data. However, other sounds may be utilized as a predetermined sound for ensuring proper placement in other embodiments.

[0311] Once we have a first spike between 75 Hz and 250 Hz, a second spike is analyzed (75), as different from the first and less than 3,000 Hz (feature [75]). If the second spike is not found in this range, we declare stenosis at less than 25%. If the second spike is in this range, then we can calculate stenosis by peak comparison using the formula. We use the formula (1−f.sub.1/f.sub.2)×100%, where f.sub.1 is the base frequency for the ring vortices in the artery (between 60 Hz and 260 Hz) and f.sub.2 is the frequency from the restricted ring vortices (below 3,000 Hz). If f.sub.1 is not present, the artery is too stenosed to show a base ring vortex and therefore we conclude there is a very high level of stenosis. If f.sub.2 is not present, then we conclude that there is insufficient stenosis to create a restricted ring vortex and thus we say there is a very low level of stenosis. If neither f.sub.1 nor f.sub.2 are present, the patient is stenosed to the point where ring vortices can no longer form. This patient has extremely high stenosis and needs to see a specialist as soon as possible.

Example of Data Analysis

[0312] Read in data and look for extraordinary features. The step is important for reviewing if the device has followed protocol or not, and whether the subject has complied with the data acquisition procedures.

[0313] The function CVRData provides a popup menu asking a user to select data, followed with a graph plotting channels, selected from left (channel 1), right (channel 2), or center (channel 3). One or all channels can be selected.

[0314] The data of FIG. 40 depicts wherein y=CVRData. The variable y contains all three channels. Additional analysis in selecting channels is provided in a further step. The output of FIG. 10 was constructed from “plot3ch.m”. The subject ID appears in the title of the last panel.

[0315] To select a channel to analyze, we look at the following aspects:

[0316] Ch=1; note that left is Ch=1, right is Ch=2, and center is Ch=3.

[0317] Setup of basic parameters for data analysis. Variable x is one of the channels in the following formula x=y(ch:3:length(y));

[0318] F.sub.s is the sampling rate, wherein F.sub.s=20,000;

[0319] One second record: the variable t is used for data visualization by plotting the first F.sub.s or one second record of the channel values. Accordingly, we can use the data:

[0320] t=(0:F.sub.s)/F.sub.s; subplot(111), plot(x(1:10*Fs)), title (‘Ten second channel plot’)

[0321] The resulting channel plot is depicted in FIG. 41.

[0322] A periodogram is generated. In general, one way of estimating the PSD of a process is to simply find the discrete-time Fourier transform of the samples of the process (usually done on a grid with an FFT) and appropriately scale the magnitude squared of the result. This estimate is called the periodogram.

[0323] Periodogram(x, hamming(length(x)), length(x), F.sub.s); xlabel(′Frequency (Hz)′).

[0324] FIG. 42 depicts the periodogram PSD estimate.

[0325] The number of frequencies plotted is 1+half of length(x) and the unit is hertz (Hz).

[0326] Welch's method can be used as an improved estimator of the PSD. Welch's method, as known to a person of ordinary skill in the art, consists of dividing the time series data into (possibly overlapping) segments, computing a modified periodogram of each segment, and then averaging the PSD estimates. The result is Welch's PSD estimate.

[0327] The averaging of modified periodograms tends to decrease the variance of the estimate relative to a single periodogram estimate of the entire data record. Although overlap between segments introduces redundant information, this effect is diminished by the use of a nonrectangular window, which reduces the importance or weight given to the end samples of segments (the samples that overlap).

[0328] However, as mentioned above, the combined use of short data records and nonrectangular windows results in reduced resolution of the estimator. In summary, there is a tradeoff between variance reduction and resolution. Once can manipulate the parameters in Welch's method to obtain improved estimates relative to the periodogram, especially when the SNR is low. This is illustrated in the following example:

[0329] A signal such as x consisting of the left channel data pwelch(x); which is graphically represented in FIG. 43.

[0330] The graph of FIG. 43 depicts the normalized frequency.

[0331] Parameters to be specified with the Welch's method must be considered. The first parameter is the segment length. Default length is (x)/8. In code we use SGM=100,000. The next parameter is percent of overlaps: noverlaps=50,000.

[0332] Through these elections we obtain Welch's overlapped segment averaging PSD estimate of the preceding signal. Use a segment length of 100,000 samples with 50 overlapped samples. Use 1+length(x)/2 DFT points so that 100 Hz falls directly on a DFT bin. Input the sample rate to output a vector of frequencies in hertz. We can plot the result.

[0333] Example: [Pxx,F]=pwelch(x, SGM, noverlaps, [ ], F.sub.s); plot (f, 10*log10(Pxx)). The result is the plot of FIG. 44.

[0334] We can further estimate PSD through autoregressive PSD estimate through use of Burg's Method. Burg's Method is a parametric method for estimating PSD. Below returns a frequency vector, F, in cycles per unit time. The sampling frequency, F.sub.s, is the number of samples per unit time. If the unit of time is seconds, then F is in cycles per second (Hz). For real-valued signals, F spans the interval [0,F.sub.s/2] when N.sub.fft is even and [0,F.sub.s/2] when N.sub.fft is odd.

[0335] The following formula assumes an AR(50) model to the data.

[0336] [Pxx,F]=pburg(x, 50, [ ], F.sub.s); plot(F,10*log10(Pxx)). The result is plotted in FIG. 45. A comparison between FIGS. 14 and 15 shows a much clearer set of peaks, allowing clearer determination of the stenosis.

[0337] We use AR(50) because we tested model orders starting from 5 through 50 and determined that AR(50) provided the cleanest data result.

Reflection Coefficients for Model Order Determination

[0338] The reflection coefficients are the partial autocorrelation coefficients scaled by −1. The reflection coefficients indicate the time dependence between y(n) and y(n−k) after subtracting the prediction based on the intervening k-1 time steps.

[0339] Use of arburg to determine the reflection coefficients. Use the reflecting coefficients to determine an appropriate AR model order for the process and obtain an estimate of the process PSD. We use the following formula:

[0340] [a,e,k]=arburg(x,50);

[0341] Stem(k, ‘filled’); title(‘Reflection Coefficients’); xlabel(‘model Order’)

[0342] FIG. 46 depicts the resultant Reflection Coefficients.

[0343] To find frequencies, we zoom into the data. Bf=0.1000/129:3876

[0344] Plot (0:1000/129:3876, 10*log10(Pxx(1:51)))

[0345] Legend (‘pburg PSD Estimate’); x label (‘Frequency (Hz)’); y label (‘Power/frequency (dB/Hz)’); title (‘PSD before denoising’). The result is the data of FIG. 47.

[0346] We can then experiment with several choices of parameters in the Welch's PSD estimate, for example, with 20% overlaps. SGM=10,000; noverlaps=2000; [Pxx,F]=pwelch9x, SGM, noverlaps, [ ], F.sub.s); plot(F,10*log10(Pxx)). This results in the plot of FIG. 48.

[0347] We can also test PSD by Welch with no overlaps:

[0348] SGM=10000; noverlaps=0; [Pxx,F]=pwelch(x, SGM, noverlaps, [ ], F.sub.s);

[0349] Plot(F,10*log10(Pxx)); xlabel(‘Frequency (Hz)’); ylabel(‘Magnitude (dB)’); title (‘PSD before denoising’). This results in the plot of FIG. 49.

[0350] If we zoom in the range of 2 kHz, with:

[0351] Uf=2000; plot (F1:uf), 10*log10(Pxx)1:uf)))

[0352] xlabel(‘Frequency (Hz)’); ylabel(‘Magnitude (dB)’); title (‘PSD before denoising’). This results in the plot of FIG. 50.

[0353] Finally, we can output with frequencies, for peak analysis with [Pxx, F]=pburg(D1, 50, [ ], Fs0′ and zoom to within 2,000 Hz (though 3,000 Hz would be good as well).

[0354] Plot(0;1000/129:1938, 10*log10(Pxx(1:26))) grid on;

[0355] Legend(‘pburg PSD estimate’)

[0356] xlabel(‘Frequency (Hz)’); ylabel(‘Magnitude (dB/Hz)’); title (‘Parametric PSD after denoising’). This results in the plot of FIG. 51

[0357] We then allow the software to define the peaks. Once identified, the peaks can be used to calculate stenosis by

[00004]$\left(1-\frac{d}{D}\right)\times 100.$

[0358] Accordingly, we know that ambient noise is present in any data set and we know some of the sounds that are always present. Furthermore, we know the sounds that we are trying to detect and have determined that these sounds are at range 20 Hz-3,000 Hz. We can remove other sounds introduced through these sensitive machines and concept is to provide a claim that covers the external and internal steps being applied to generate clean data.

[0359] In certain embodiments, we determine stenosis based upon a class of stenosis. For example, a first class may be less than 25% stenosis. A second class may be less than 50% stenosis, less than 70% stenosis, less than 90% stenosis. Accordingly, a method may be to calculate a binary response of less than or more than 25% stenosis. Another method may be to calculate a binary response of less than or more than 50% stenosis. Another method may be to calculate a binary response of less than 70% or less than 90% stenosis.

[0360] Calculation of stenosis in such binary decision charts allows for a broad and quick determination of risk to a patient. Furthermore, certain procedures may be medically recommended at a certain stenosis percentage. Accordingly, for example, when testing the coronary artery, it may be necessary only to determine a binary decision of more or less than 50% stenosis, as procedures are recommended for surgical action once stenosis reaches such threshold.

[0361] Utilizing the devices, systems, and methods as described above, the present components can be utilized in a system to identify large ring vortices from a fluid flow vessel. We can then analyze the signal utilizing low frequency (spectral) methods and assess the range of stenosis, occlusion.

[0362] In preparing for a test, the system first goes through a series of calibration steps, ensuring correct receipt of the signals, correlating the signals from the two carotid arteries and the heart, and identifying the systolic time, the period of most rapid fluid flow. Once the signal is recorded, the system prepares the data for processing the digital signal to conduct a spectral analysis. Using the signal features, a statistical analysis is performed against multiple parameters to render a classification of degree of stenosis, occlusion, or aneurysm within each fluid flow vessel. For stenosis of the carotid artery, the output renders a report indicating a range of blockage against the defined NASCET categories with a representation of the systolic events.

[0363] In accordance with one embodiment, the sensor array one or more sensors, which are positioned proximate the fluid flow vessel to be examined. In some instances, the sensors are placed onto an array for determination of stenosis of the carotid artery. An array comprises two branches, which are biased inward and can be bent/flexed outward to the proper position. To accommodate bodies of differing heights, additional modifications can be made to allow for the adjustment of the lower sensor with respect to the upper sensors (e.g., providing a telescoping or otherwise extendable portion or arrangement in the lower branch and/or the upper two branches).

[0364] A particular feature of the array is that it is adjustable and can be configured to account for the anatomical differences between individuals, while remaining sufficiently rigid to support the sensing elements. Furthermore, the shape and design of the array is particular important to assist with orienting sensing elements to each portion of the array, wherein sensing elements can easily be positioned adjacent to the neck for appropriate positioning to sense the carotid artery. At the same time, the materials and the angles utilized in the array provide appropriate resistance and a gentle force to compress the sensing element to the side of the neck for sensing. The shape and material thus provide an important feature to gently, but securely assist in positioning of the sensing elements and for testing patients for stenosis of the carotid artery.

[0365] The array is adjustably designed to fit a majority of adults and to be held by the patient or a third person when performing a carotid artery test. In a preferred embodiment, the array, when placed on the patient, imparts sufficient pressure on the patient so as to achieve a measurement of sufficient quality to accurately determine stenosis, while limiting the pressure applied to the carotid artery. The goal is for there to be sufficient pressure to assist in positioning the sensing elements and maintaining their position for about 2-3 minutes during a test, but not such pressure as to significantly impact the shape and size of the carotid artery being assessed. Indeed, as a whole, the array and the sensing elements are designed to be a passive test that is nonemitting, noninvasive, and is configured so that anyone can conduct the test without requiring certification.

[0366] In accordance with one embodiment, the sensor elements in collaboration with the software or application running on a PC or main computing unit, takes three readings simultaneously from the right and left carotid arteries in the neck and from the heart just below the sternum, calibrates the sound signature, filters, and then digitizes data for analysis. A shielded cable transmits the signals to the main computing unit. In further embodiments, signals and data can be transmitted via other transmission means, including wireless, Bluetooth, or other suitable data transmission mechanisms.

[0367] Therefore, a method for determining stenosis of the carotid artery in a human patient consists of a first step of placing a sensing device onto the patient, wherein a first sensing element is placed adjacent to the carotid arteries; the sensing elements then measure sounds from the carotid artery. The sound is measured in analog and modified to digital format and then analyzed before a power spectral density analysis is performed. The power spectral density graph reveals peaks that are then analyzed to provide for a calculation of percent stenosis or occlusion of the carotid artery.