Distortion compensation for bone anchored hearing device

Abstract

A bone anchored hearing device includes an electromagnetic vibrator for generating a vibration in order to transmit sound through a bone of a user to an ear of the user; and a compensator for at least in part compensating a distortion in the vibration of the electromagnetic vibrator. Further, a signal processing method for a bone anchored hearing device includes providing, by an input transducer, an electric input signal representing sound of a surrounding of a user of the bone anchored hearing device; processing, by a signal processing unit, the electric input signal and providing a processed electric signal; generating, by an electromagnetic vibrator, based on the processed electric signal, a vibration in order to transmit sound through a bone of the user to an ear of the user; and at least in part compensating, by a compensator, a distortion in the vibration of the electromagnetic vibrator.

Claims

1. A bone anchored hearing device comprising: an input transducer configured to provide an electric input signal representing sound of a surrounding of a user of the bone anchored hearing device; a signal processing unit configured to process the electric input signal and provide a processed electric signal; an electromagnetic vibrator for generating a vibration in order to transmit sound through a bone of a user to an ear of the user based on the processed electric signal; and a compensator for at least in part compensating a distortion in the vibration of the electromagnetic vibrator, wherein a compensation of the distortion is based on a dependence of a driving force acting on a vibrating component of the electromagnetic vibrator on a displacement of the vibrating component.

2. The bone anchored hearing device of claim 1, wherein the distortion is one or more of a harmonic distortion in the vibration; an inharmonic distortion in the vibration; and/or a distortion due to an asymmetric behavior of the electromagnetic vibrator.

3. The bone anchored hearing device of claim 2, wherein the compensator is configured for receiving an uncompensated signal and/or for providing a compensated signal to the electromagnetic vibrator for at least in part compensating the distortion in the vibration of the electromagnetic vibrator.

4. The bone anchored hearing device of claim 2, wherein the electromagnetic vibrator is a variable reluctance vibrator.

5. The bone anchored hearing device of claim 2, wherein the electromagnetic vibrator comprises one or more of: a magnet and/or a coil for generating vibrations so as to transmit sound through the bone to the ear; an anchor for connecting the electromagnetic vibrator to an abutment or implant; and/or an air gap between the magnet and/or coil and the anchor.

6. The bone anchored hearing device of claim 1, wherein the compensator is configured for receiving an uncompensated signal and/or for providing a compensated signal to the electromagnetic vibrator for at least in part compensating the distortion in the vibration of the electromagnetic vibrator.

7. The bone anchored hearing device of claim 6, wherein the compensation signal is comprised by a supply voltage of the electromagnetic vibrator, in particular of a coil of the electromagnetic vibrator.

8. The bone anchored hearing device of claim 7, wherein the electromagnetic vibrator is a variable reluctance vibrator.

9. The bone anchored hearing device of claim 6, wherein the electromagnetic vibrator is a variable reluctance vibrator.

10. The bone anchored hearing device of claim 6, wherein the electromagnetic vibrator comprises one or more of: a magnet and/or a coil for generating vibrations so as to transmit sound through the bone to the ear; an anchor for connecting the electromagnetic vibrator to an abutment or implant; and/or an air gap between the magnet and/or coil and the anchor.

11. The bone anchored hearing device of claim 1, wherein the electromagnetic vibrator is a variable reluctance vibrator.

12. The bone anchored hearing device of claim 1, wherein the electromagnetic vibrator comprises one or more of: a magnet and/or a coil for generating vibrations so as to transmit sound through the bone to the ear; an anchor for connecting the electromagnetic vibrator to an abutment or implant; and/or an air gap between the magnet and/or coil and the anchor.

13. The bone anchored hearing device of claim 1, further comprising one or more of: an implant for implantation into the bone; an abutment for connection with the implant; an input transducer for receiving sound from a surrounding of the user and providing an electric input signal representing the sound; a receiving coil for receiving electromagnetic signals; an amplifier for amplifying an electric signal; and/or a signal processing unit for processing the electric input signal and providing a processed electric signal.

14. The bone anchored hearing device of claim 1, wherein the compensator is configured for one or more of: modifying a driving force acting on a vibrating component of the electromagnetic vibrator; modifying a supply voltage of the electromagnetic vibrator; and/or modifying the supply voltage of the electromagnetic vibrator depending on a displacement of the vibrating component of the electromagnetic vibrator.

15. The bone anchored hearing device of claim 1, wherein the compensator is configured to provide a compensated signal to the electromagnetic vibrator such that the driving force is substantially independent of the displacement of the vibrating component.

16. A signal processing method for a bone anchored hearing device, in particular a bone anchored hearing device according to claim 1, the method comprising: providing, by an input transducer, an electric input signal representing sound of a surrounding of a user of the bone anchored hearing device; processing, by a signal processing unit, the electric input signal and providing a processed electric signal; generating, by an electromagnetic vibrator, based on the processed electric signal, a vibration in order to transmit sound through a bone of the user to an ear of the user; and at least in part compensating, by a compensator, a distortion in the vibration of the electromagnetic vibrator, wherein a compensation of the distortion is based on a dependence of a driving force acting on a vibrating component of the electromagnetic vibrator on a displacement of the vibrating component.

17. The signal processing method of claim 16, the compensating comprising: compensating a harmonic distortion in the vibration; compensating an inharmonic distortion in the vibration; and/or compensating a distortion due to an asymmetric behavior of the electromagnetic vibrator.

18. The signal processing method of claim 16, the compensating comprising: modifying a driving force acting on a vibrating component of the electromagnetic vibrator; modifying a supply voltage of the electromagnetic vibrator; and/or modifying the supply voltage of the electromagnetic vibrator depending on a displacement of the vibrating component of the electromagnetic vibrator.

19. The signal processing method of claim 16, the compensating comprising generating a driving force acting on a vibrating component of the electromagnetic vibrator, wherein the driving force is substantially independent of a displacement of the vibrating component.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effects will be apparent from and elucidated with reference to the illustrations described hereinafter in which:

(2) FIG. 1 schematically illustrates an electromagnetic vibrator;

(3) FIG. 2A schematically illustrates a further electromagnetic vibrator;

(4) FIG. 2B schematically illustrates some components of a bone anchored hearing device comprising the electromagnetic vibrator of FIG. 2A;

(5) FIG. 3 schematically illustrates a simplified electromagnetic vibrator;

(6) FIG. 4 comprises panels (A)-(D), wherein panels (A) and (B) schematically illustrate a supply voltage and a magnetic force both as a function of a distance between a magnet and an anchor for a constant supply voltage, and wherein panels (C) and (D) schematically illustrate a supply voltage and a magnetic force according to an exemplary embodiment both as a function of the distance between the magnet and the anchor for a varying supply voltage;

(7) FIG. 5 schematically illustrates a block diagram of some components of a bone anchored hearing device according to an exemplary embodiment;

(8) FIG. 6A schematically illustrates a magnetic force as a function of a displacement of a vibrating component for a real motion and for an ideal motion; and

(9) FIG. 6B schematically illustrates the magnetic force shown in FIG. 6A and further a compensation signal according to an exemplary embodiment as a function of the displacement of the vibrating component.

DETAILED DESCRIPTION

(10) The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts.

(11) However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the apparatus and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

(12) In the following the same reference numerals will be used for the same components also in different embodiments.

(13) FIG. 1 shows a schematic illustration of a cross section of an electromagnetic vibrator 100 comprising a magnet 8 and a coil 7 arranged around a part of the magnet (an example of the electromagnetic component), and an anchor A (an example of a vibrating component) connecting the electromagnetic vibrator 100 to an abutment 30 (an example of, part of, and/or being connected to an implant). An air gap is located in between the magnet 8, the coil 7 and the anchor A. The anchor A is further connected to a housing by means of one or more springs 40, wherein the housing encloses the magnet 8 and the coil 7. The magnet 8 comprises wolfram, in particular the magnet 8 consists of approximately 98% wolfram. When a supply voltage is provided to the electromagnetic vibrator 100, the magnet 8 and the coil 7 transfer a magnetic force to the anchor A, and the anchor A moves along a longitudinal direction (shown as double arrow) applying a vibrational force to the abutment 30, which in turn transfers the vibrational force to an implant such as a titanium screw, thereby transferring the vibration onto the skull of the patient.

(14) FIG. 2A shows a cross section of a further transducer in the form of an electromagnetic vibrator 100 having a casing bottom 1, a vibrator plate 2, a vibrator plate ring 3, a vibrator spring 4 and spring ring 21. Casing bottom 1 is similar to the anchor shown in FIG. 1. In a tungsten frame 5, there is arranged a bobbin 6 and a coil 7. Between the frame 5 and the coil 7 there is arranged a magnet 8. Casing bottom 1 receives a vibration from an electromagnetic component comprising magnet 8 and coil 7 and transfers the vibration via the above components onto the skull of the patient. The transducer further comprises a casing top 9 and casing lid 10 for closing the transducer. There is provided a feedthrough 10 for allowing a control signal and/or supply voltage to be provided to the transducer. The feedthrough pin 13 may be contacted via a solder 14. The transducer may comprise electronic circuits, e.g. on a PCBA 11. In this example, the PCBA may include a signal processing unit that may include a compensator 400 configured to at least in part compensating a distortion in the vibration of the electromagnetic vibrator 100. At places 15, 16 glue may be used for fixation and/or sealing of the respective components. In this case, the complete electromagnetic vibrator is an implant and the electromagnetic vibrator is arranged between a skin layer and the skull of the patient.

(15) FIG. 2B shows some components of a bone anchored hearing device 1000 comprising an (output) transducer 100 (an example of an electromagnetic vibrator, such as the one described above), a neck 200, and an antenna 300. Thereby, the antenna 300 comprises a magnet assembly 310 and a receiving coil 320, both being embedded into silicone. The neck 200 comprises a reinforcement 210 in order to prevent breakage and/or tearing of the device at the neck. For fixing the device to the skull of the patient, the transducer 100 is attached to a fixation band 400, which in turn may be fixed to the skull of the patient. The components shown in FIG. 2B may be wholly implantable. The compensator 400 may either be arranged within the antenna 300 or within the transducer 100 on a PCB electrically connected to the receiving coil 320.

(16) FIG. 3 shows a schematic illustration of a simplified electromagnetic vibrator 100 for a bone anchored hearing device comprising an electromagnet A (an example of the electromagnetic component) and an anchor B (an example of the vibrating component). Electromagnet A may be induced by the (amplified) electric input signal and, by means of a magnetic force following the electric input signal, i.e. the supply voltage, make anchor B move along a longitudinal direction, the longitudinal direction being indicated by the double arrow. Thereby, as described above, the magnetic force between electromagnet A and anchor B is inversely proportional to the distance between A and B squared. I.e., when anchor B moves away from electromagnet A, the magnetic force gets weaker and when anchor B moves closer to electromagnet A, the magnetic force gets stronger. Simplified, the proportionality may be exemplified in that if the distance gets doubled the magnetic force will be four times weaker and if the distance gets halved, the magnetic force will be four times stronger.

(17) As a result, the anchor will move in an asymmetrical way for a symmetrical signal, e.g. a sinusoidal signal. The asymmetrical movement leads to a distorted sinusoidal signal that may be measurable and/or hearable by the patient, e.g. when playing loud music.

(18) In other words, for small signals, i.e. small movements of the anchor, the distortion is small. For larger signals, i.e. larger movements of the anchor, the distortion increases, thereby possibly becoming measurable and/or hearable.

(19) FIG. 4 shows panels (A)-(D). All quantities shown in FIG. 4 are given in arbitrary units, meaning that a behavior of the quantities may only be interpreted qualitatively.

(20) Panel (A) shows a supply voltage of an electromagnetic vibrator (solid horizontal line) as a function of a distance between a magnet and an anchor of the electromagnetic vibrator for a constant supply voltage (a constant supply voltage profile). Panel (B) shows a magnetic force between the magnet and the anchor (solid line) as a function of the distance for a constant supply voltage as shown in panel (A). As can be seen in panel (B), as the distance increases from 0 to 1, the magnetic force decreases. Ideally, the magnetic force should be the same no matter where the magnet and/or anchor are (dashed horizontal line). The rest position of the anchor and/or the magnet is shown as a vertical, dashed line (panels (A) and (B)).

(21) Panel (C) shows a supply voltage (solid line) according to an exemplary embodiment as a function of the distance between the magnet and the anchor. Thereby, the supply voltage is not constant as in panel (A), but varies depending on the distance. Specifically, as the distance increases from 0 to 1, the supply voltage increases as well. Panel (D) shows the magnetic force (solid grey line) as a function of the distance for a constant supply voltage as shown in panel (A), and the varied supply voltage (solid black line) shown in panel (C). As can be seen, the dependence of the supply voltage on the distance is the exact opposite of the dependence of the magnetic force on the distance. As a result, as can be seen in panel (D), the dependencies of the supply voltage and the magnetic force on the distance cancel out, such that a constant magnetic force (dashed horizontal line) between the magnet and the anchor is achieved. In practical, there may appear some small variations in the supply voltage due to load variations on the power storage, and therefore, the resulting magnetic force does not become ideally constant, but the unwanted variation in the magnetic force has been reduced significantly. As described in detail above, such a constant magnetic force or nearly constant magnetic force is advantageous in terms of avoiding measurable and/or hearable distortions of the vibration and thereby improving user experience of the bone anchored hearing device.

(22) FIG. 5 shows a block diagram of some components of a bone anchored hearing device comprising a microphone (“MIC1”), a chip including an amplifier, a compensator, an input port for adding the compensation signal and an (electromagnetic) vibrator. The input port is connected to the compensator 400 which is also part of the bone anchored hearing device. The compensation signal may be applied at several stages along a path of the electric signal. As shown in FIG. 5, the input port for adding the compensation signal may be located in between the chip including the amplifier and the electromagnetic vibrator. Adding the compensation signal right before the electromagnetic vibrator is advantageous as it allows for adding the compensation signal right before the processed electric signal is used by the electromagnetic vibrator to generate a vibration, thereby avoiding possible noise which might be introduced to the compensation signal, for example in case the compensation signal would be added earlier on. However, other locations for adding the compensation signal, e.g. in between the microphone and the chip, are possible as well. In this example the compensation signal includes a supply voltage for the vibrator, and wherein the supply voltage is determined based on the uncompensated signal received from the chip. In another example, the compensator is connected to a memory which includes a measured distortion as a function of a supply voltage of the vibrator. In this example, the compensator is configured to determine the compensation signal based on the uncompensated signal and the measured distortion.

(23) FIG. 6A shows the magnetic force as a function of the displacement of the vibrating component for a real motion and for an ideal motion. FIG. 6A shows the same relationship which is shown in FIG. 4, panel (B), whereby here, the x-axis shows the displacement of the vibrating component from its resting position (−30 to +30) instead of the distance between the magnet and the anchor (0 to 1). In other words, FIG. 6A shows a simulation of the magnetic force in the air gap between the magnet and/or coil and the anchor. Thereby, the solid horizontal line shows the magnetic force of an ideal electromagnetic vibrator, the magnetic force being constant for a whole working range of the electromagnetic vibrator.

(24) The solid curved line, on the other hand, shows a simulation of a movement due to the asymmetrical behavior of the electromagnetic vibrator (real motion). Thereby, when the vibrating component moves away from the electromagnetic component (positive displacement), the magnetic force gets weaker, and when the vibrating component moves closer to the electromagnetic component (negative displacement), the magnetic force gets stronger. A displacement of zero indicates the vibrating component being in its resting position.

(25) It should be noted that in praxis the magnetic field extends beyond the air gap and hence the magnetic field is more homogeneous. In praxis, a deviation of the real motion from the ideal motion therefore is smaller than shown in FIG. 6A. In praxis, the deviation of the magnetic force in an electromagnetic vibrator will be less than or equal to 10%, in particular less than or equal to 5%. However, even such a relatively small deviation is unwanted as it might also induce measurable and/or hearable distortions.

(26) FIG. 6B shows the same magnetic forces shown in FIG. 6A, but further includes the compensation signal according to an exemplary embodiment as a function of the displacement of the vibrating component. In other words, FIG. 6B shows the same relationship which is shown in FIG. 4, panel (D), whereby the x-axis shows the displacement of the vibrating component from its resting position (−30 to +30) instead of the distance between the magnet and the anchor (0 to 1). Thereby, the compensation signal mirrors the asymmetrical movement of the anchor such that the compensation signal cancels out the asymmetric movement of the anchor, which alone would generate distortions. After adding the compensation signal to the electric input signal, an actual movement of the anchor will be the same as a movement of the anchor in case of a constant magnetic force through the whole movement, i.e. will equal the ideal motion (solid horizontal line).

(27) A computer program (product) comprising instructions which, when the program is executed by a computer, cause the computer to carry out (steps of) the method described above, in the ‘detailed description of embodiments’ and in the claims is furthermore provided by the present application.

(28) In an aspect, the functions may be stored on or encoded as one or more instructions or code on a tangible computer-readable medium. The computer readable medium includes computer storage media adapted to store a computer program comprising program codes, which when run on a processing system causes the data processing system to perform at least some (such as a majority or all) of the steps of the method described above, in the and in the claims.

(29) By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. In addition to being stored on a tangible medium, the computer program can also be transmitted via a transmission medium such as a wired or wireless link or a network, e.g. the Internet, and loaded into a data processing system for being executed at a location different from that of the tangible medium.

(30) In an aspect, a data processing system comprising a processor adapted to execute the computer program for causing the processor to perform at least some (such as a majority or all) of the steps of the method described above and in the claims is provided.

(31) It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

(32) As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, but an intervening element may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

(33) It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.

(34) Accordingly, the scope should be judged in terms of the claims that follow.