HEARING PROTECTION DEVICE HAVING DOSIMETER WITH ALERTING FUNCTION

Abstract

A system including an acoustic barrier suitable for wearing in or on an ear of an individual mammalian subject, and a processor. The acoustic barrier defines at least one sound path therethrough and includes a microphone for measuring sound pressure inside the acoustic barrier. The processor is arranged to receive measurements from the microphone and determine a risk that a sound dose limit will be reached before a predetermined time associated with the dose limit. The system is arranged to provide an indication of the determined risk.

Claims

1. (canceled)

2. (canceled)

3. A hearing protection device suitable for wearing in or on an ear of an individual mammalian subject to form an acoustic barrier, comprising a microphone for measuring sound pressure inside the acoustic barrier and a warning system arranged to determine whether a sound dose limit will be reached based on signals from said microphone wherein said warning system is arranged to calculate a determined risk using a number of instances of a predetermined threshold of amplitude of noise being exceeded in a time period and to provide an indication of said determination whether a sound dose limit will be reached.

4. The hearing protection device as claimed in claim 3, wherein the hearing protection device comprises a device for insertion into an ear canal.

5. The hearing protection device, as claimed in claim 3, wherein the hearing protection device provides a maximum attenuation of at least 15 dB.

6. The hearing protection device, as claimed in claim 3, wherein the hearing protection device cannot be connected to a user's external sound reproduction device.

7. The hearing protection device, as claimed in claim 3, wherein the processor or warning system is arranged to calculate an accrued noise exposure from an initial start time.

8. The hearing protection device, as claimed in claim 7, wherein the processor or warning system is arranged to calculate the accrued noise exposure by recording periodic measurements of the sound pressure behind the acoustic barrier.

9. The hearing protection device, as claimed in claim 7, wherein the processor or warning system is arranged to predict an estimated total accrued noise exposure by extrapolating the accrued noise exposure and comparing the estimated accrued noise exposure and the sound dose limit.

10. The hearing protection device, as claimed in claim 3, wherein the processor or warning system is further arranged to calculate the determined risk using a rate of change of accrued noise exposure.

11. The hearing protection device, as claimed in claim 3, arranged to provide an indication when there is a risk of the sound dose limit being exceeded before a or the predetermined time is reached.

12. (canceled)

13. The hearing protection device, as claimed in claim 3, arranged to provide one or more indications to an individual or system other than the user.

14. (canceled)

15. The hearing protection device, as claimed in claim 3, comprising a further device arranged to provide the indication in the form of an alert.

16. (canceled)

17. The hearing protection device, as claimed in claim 3, wherein only one indication is provided when a predefined determined risk is reached.

18. The hearing protection device, as claimed in claim 3, arranged to adjust an attenuation provided by the acoustic barrier in response to a determined risk.

19. (canceled)

20. A method comprising: measuring a sound pressure inside an acoustic barrier; determining a risk that a sound dose limit will be reached before a predetermined time associated with the dose limit by using a number of instances of a predetermined threshold of amplitude of noise being exceeded in a time period; and providing an indication of the determined risk.

21. The method as claimed in claim 20, further comprising calculating an accrued noise exposure from an initial start time.

22. The method as claimed in claim 21, wherein calculating the accrued noise exposure comprises recording periodic measurements of the sound pressure behind the acoustic barrier.

23. The method as claimed in claim 21, further comprising predicting an estimated total accrued noise exposure by extrapolating the accrued noise exposure and comparing the estimated accrued noise exposure and the sound dose limit.

24. The method as claimed in claim 20, further comprising determining the risk using a rate of change of accrued noise exposure.

25. The method as claimed in claim 20, comprising providing an indication that there is a risk of the sound dose limit being exceeded before the predetermined time is reached.

26. The method as claimed in claim 20, comprising adjusting the attenuation provided by the acoustic barrier in response to the determined risk.

Description

[0039] It will be appreciated that the optional features of any aspect of the present invention may also be optional features of any other aspect of the present invention disclosed.

[0040] A selection of embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawing in which:

[0041] FIG. 1 shows a user implementing a system as described in the form of an over-the-ear acoustic barrier;

[0042] FIG. 2 shows an exemplary over-the-ear acoustic barrier device;

[0043] FIG. 3 shows an exemplary in-ear acoustic barrier device;

[0044] FIG. 4 shows an exemplary method of providing an indication of the determined risk; and

[0045] FIG. 5 shows a graph of squared pressure against time.

[0046] FIG. 1 is an exemplary embodiment of a system 100 in accordance with the present invention for use by an individual 102 in a high amplitude noise environment. The individual may be an employee who regularly works in a high amplitude noise environment e.g. a construction worker, sound technician, warehouse worker, musician, tree surgeon etc.

[0047] The individual is provided with an acoustic barrier device in the form of a pair of over-the-ear defenders 104 to help to protect against damage to their hearing resulting from exposure to high amplitude noise over a prolonged period of time. The pair of over-the-ear defenders 104 enclose the entire ears of the individual 102 and thus provide the acoustic barrier. More details can be found below in relation to FIG. 2.

[0048] In accordance with the invention and as described in more detail below, the system 100 is arranged to measure exposure to sound and to calculate a risk that sound exposure limit will be reached before a predetermined time—e.g. the end of their shift. A number of devices for indicating the determined risk are provided in this embodiment but only one or fewer of these may be used and other ways of indicating this risk not described could be implemented instead.

[0049] As shown in FIG. 1, the over-the-ear defenders 104 comprise a light 106. The light 106 may be a light emitting diode or a small filament bulb. This light provides an indication to workers or supervisors in the vicinity of the individual 102 of the individual's determined risk. For example, the light 106 being on may indicate that the individual's determined risk is above a certain threshold e.g. that the user is expected to exceed the sound dose limit before the end of their shift. Alternatively, the light 106 turning on may indicate to others that more drastic action needs to be taken e.g. that the individual has exceeded the sound dose limit (before the end of their shift) and need to leave the high amplitude noise region immediately. The light 106 may also in some embodiments emit different coloured light depending on the determined risk.

[0050] The system 100 further includes a mobile device 108. This mobile device 108 may belong to the individual 102, but could in other embodiments belong to other personnel (e.g. the individual's manager). The over-the-ear defenders may have a built-in processing unit (not seen in FIG. 1) which is arranged to transmit information regarding the determined risk to the mobile device 108. The mobile device 108 can then provide an alert to the user via, for example, an application on the mobile device 108. The mobile device 108 may be configured to provide a haptic alert to an individual 102. In other examples, the processing unit (not shown in FIG. 1) is provided by the mobile device 108. Such a mobile application may receive transmitted relevant information from the over-the-ear protection device 104 (e.g. sound pressure measured behind the acoustic barrier, accrued noise exposure), and use this information to calculate the determined risk using specialist algorithms.

[0051] In a similar manner to that described for the light 106 provided on the over-the-ear protection, the mobile device 108 may be configured to provide different alerts depending on the determined risk. For example, a vibration may be provided to alert the user that the determined risk has exceeded a certain predetermined threshold. In a complementary or alternative embodiment, the mobile device 108 may persistently vibrate when the determined risk has exceeded a certain predetermined threshold and/or when individual has exceeded the sound dose limit (before the end of their shift). The vibration may persist until the individual 102 interacts with the mobile device 108 to acknowledge they have received the alert.

[0052] The system 100 further comprises a central database 110. The processor in the over-the-ear protection 104 may transmit information e.g. the sound pressure measured inside the acoustic barrier, accrued noise exposure or determined risk, to the central database 110. The central database 110 can record this information relating to the exposure of an individual 102 to high amplitude noises. The recorded information can be used to track the individual's exposure over a longer period of time. It may also allow the individual 102 or other relevant personnel (e.g. the individual manager) access to this information.

[0053] There are a number of different components which may comprise the pair of over-the-ear defenders. FIG. 2 show an exemplary cross-section of one of a pair of over-the-ear defenders 200.

[0054] The over-the-ear defender 200 shown in FIG. 2 comprises an outer layer 202 which is intended to provide an acoustic barrier and thus reduce the sound pressure level inside the acoustic barrier compared with outside the acoustic barrier. The over-the-ear defender 200 further comprises a microphone 204 behind the acoustic barrier, a loudspeaker 206 also behind the acoustic barrier and a processing unit 208.

[0055] The microphone 204 measures the sound pressure behind the acoustic barrier 202. The microphone 204 may continuously record the sound pressure or may only be actively powered and record the sound pressure at certain time intervals (e.g. every minute). The microphone provides the measurement of the sound pressure level to the processing unit 208.

[0056] The processing unit 208 then uses the measurement of the sound pressure level to calculate the determined risk. This calculation is discussed in more detail in relation to the method shown in FIG. 4. In the example shown in FIG. 2, the processing unit 208 comprises a transmitter 210. The transmitter 210 can transmit information such as the measured sound pressure level behind the acoustic barrier or the determined risk to a further device such as a smartwatch, tracker or mobile phone which may then provide an alert to the individual. The transmitter 210 may also transmit such information to a central database as previously described.

[0057] The over-the-ear defenders 200 shown in FIG. 2 also comprise a loudspeaker 206. The loudspeaker 206 is used to provide an indication to the individual on the determined risk. This could be in the form a tone indicating when a certain determined risk is reached. Alternatively, the loudspeaker 206 could be used to provide a quantitative alert such as an audio alert indicting the length of time remaining until it is predicted that the sound dose limit will be reached. The loudspeaker 206 may also be used for additional features of the over-the-ear defenders 200 such as playing music, communicating with other workers etc.

[0058] Although a user not wearing the ear defenders when they should be may not hear an audible alert, typically the defenders are nonetheless worn around the neck or on top of the head and as such an alert (or combination of alerts) may nonetheless be perceived.

[0059] Whilst the acoustic barrier in FIG. 1 is provided by a pair of over-the-ear defenders 104, the acoustic barrier could instead be provided by a device for insertion into the ear canal of the individual 102 and the system 100 would function in the same manner. An example of such a device is shown in FIG. 3.

[0060] The device seen in FIG. 3 is an earplug 302 which creates a seal within the ear canal of the individual. The earplug 302 comprises a microphone 304, a loudspeaker 306 and a processing unit 308. These components perform similar functions to those previously described in relation to the over-the-ear protection seen in FIG. 2. However, the processing unit 308 may in certain embodiments not be in the earplug 302 but may be located elsewhere e.g. in a mobile device, elsewhere on the user. This may be necessary due to restraints of dimensions and therefore number of components that can be contained within the ear-plug 302.

[0061] FIG. 4 is a flow diagram showing an exemplary method for estimating a risk of a predefined sound exposure dose being reached prematurely and providing an indication to an individual of the determined risk. The method shown in FIG. 4 could be implemented in any system previously described or indeed any other suitable system.

[0062] In step 402, the sound pressure inside the acoustic barrier is measured. This measurement is provided by the microphone 204, 304 in the over-the-ear protection 200 or earplug 302 depending on the system implemented. This sound measurement may be made periodically (e.g. every minute) or in other embodiments may be made continuously. The measurement of the sound pressure is then transmitted to the processing unit 208, 308. The processing unit 208, 308 can store the measured sound pressure.

[0063] In step 404, the processing unit calculates the accrued noise exposure from the stored measurements of sound pressure. In step 406, the processing unit 208, 308 then extrapolates the accrued exposure to predict the estimated total noise exposure (e.g. that the individual will have experienced by the end of their shift). In step 408, the estimated accrued noise exposure is then compared to the sound dose limit (of the individual). The processing unit 208, 308 then calculates the risk of the limit being reached too soon based on the comparison between the estimate accrued noise exposure.

[0064] In some embodiments, the processing unit may also perform the step 410 of calculating the rate of change of accrued noise exposure. This can be an important factor to account for changes in the environment of the individual. For example, the amplitude of the noise in the high amplitude noise environment may steadily increase over a period of time. As the amplitude of the noise increases, the noise exposure of an individual will increase faster. Therefore, should the rate of change of accrued noise exposure not be taken into account, then a determined risk calculated solely on the estimated total noise exposure could be an underestimate.

[0065] In step 414 the processor configures an indication of the determined risk which is provided to the individual. This determined risk could be provided to the individual via any of the mechanisms previously described. The indication of the determined risk may be transmitted by a transmitter 210, 310 to a device providing the indication.

[0066] A more detailed exemplary algorithm for predicting when a dose limit will be reached will now be described with reference to FIG. 5. This shows a graph of A-weighted sound pressure exerted on the ear drum of an individual versus time. The noise exposure dose, E is defined by Equation 1 as shown below. p.sub.A is the A-weighted sound pressure and t is time. An A-weighted pressure weights the relatively loudness of sounds in air as perceived by the human ear.

E=p.sub.A.sup.2t   [Eq.1]

[0067] More accurately the exposure E is the integral of the square of the weighted sound pressure level over time. The noise exposure dose is defined in units of Pa.sup.2 hours. 1 Pa.sup.2 hour is typically equivalent to an average allowable daily dose for an individual. This is equivalent to being subjected to an average sound pressure of 85 dBA for 8 hours. Some areas of legislation (onshore, offshore, mining, aviation, different countries) may have other daily limits than 1 Pa.sup.2 hour. In these cases, a relevant alternative value will be used in the calculation. In the following example, 1 Pa.sup.2 hour is taken to the average allowable daily dose.

[0068] With reference to the graph shown in FIG. 5, this shows the recorded squared pressure p.sup.2 against time, where p.sub.0.sup.2 is the squared pressure at the present time to. The total length of the shift is T hours. The variable p.sub.1.sup.2 is the average of the pressure history from a start time to t.sub.0. E.sub.1 is the actual accrued dose from the start time until the present time to and is the area under the curve from the start time to t.sub.0. E.sub.2 is the amount of exposure that the user is permitted to experience during the rest of the shift to exactly meet the daily dose, as given by Equation 2.

E.sub.2=1 Pa.sup.2 hour−E.sub.1   [Eq.2]

[0069] From Equation 1 and Equation 2, a pressure level p.sub.2.sup.2 can be calculated which is the maximum continuous pressure an individual can experience for the duration of the shift if the sound dose limit is not to be exceeded. Since the sound pressure level typically varies during a shift, any instantaneous measured sound pressure level may be over or under this particular level without necessarily causing the total dose to be exceeded. Therefore, the system needs to continuously evaluate and predict whether the varying levels will result in an exposure greater than the sound dose limit. The system may then provide an alert indicating that the user needs to take action e.g. improve the fit of their hearing protection or implement additional hearing protection.

[0070] Depending on the value of E.sub.2 and the current sound pressure p.sub.0, the individual may receive a number of alerts. If E.sub.2 is less than or equal to zero, then the individual may receive an alert in the form of a red light that indicates that the sound dose limit has already been exceeded (and e.g. the individual must end their shift in the high amplitude noise environment immediately). If E.sub.2 is greater than zero, and p.sub.0.sup.2 is greater than p.sub.2.sup.2 as shown in FIG. 5, then the individual receives an alert in the form of an orange light which indicates that they are expected to exceed the sound dose limit before the end of their shift (e.g. 8 hours). This may encourage the individual to move to a different environment, or take further precautions as implementing (additional) ear protection. If E.sub.2 is greater than zero, and p.sub.0.sup.2 is less than p.sub.2.sup.2, this indicates that the individual does not need to be alerted as the sound dose limit should not the exceeded. This could be indicated to the individual by a green light. More advanced methods may be required to ensure an individual is not alerted too frequently.

[0071] Thus it will be appreciated by those skilled in the art that a hearing protection system according to embodiments of the present invention may help to reduce damage to hearing caused by high amplitude noise environments. It will be further appreciated however that many variations of the specific arrangements described herein are possible within the scope of the invention as defined in the claims.