Hearing aid and processes for adaptively processing signals therein

• US 20050078842A1
• Filed: 10/09/2003
• Published: 04/14/2005
• Est. Priority Date: 10/09/2003
• Status: Active Grant

• Current Assignee: Unitron Hearing Limited (Sonova Holding AG)
• Original Assignee: Unitron Hearing Limited (Sonova Holding AG)
• Inventors: Vonlanthen, Andre, Luo, Henry, Arndt, Horst
• Granted Patent: US 6,912,289 B2
• Time in Patent Office: Days
• US Class Current: 381/312
• CPC Class Codes: H04R 2225/43 Signal processing in hearing aids to enhance the speech intelligibility
• CPC Class Codes: H04R 2410/07 Mechanical or electrical reduction of wind noise generated by wind passing a microphone
• CPC Class Codes: H04R 25/407 Circuits for combining signals of a plurality of transducers
• CPC Class Codes: H04R 25/43 Electronic input selection or mixing based on input signal analysis, e.g. mixing or selection between microphone and telecoil or between microphones with different directivity characteristics H04R25/407 takes precedence
• CPC Class Codes: H04R 25/453 electronically

Abstract

An improved hearing aid, and processes for adaptively processing signals therein to improve the perception of desired sounds by a user thereof. In one broad aspect, the present invention relates to a process in which one or more signal processing methods are applied to frequency band signals derived from an input digital signal. The level of each frequency band signal is computed and compared to at least one plurality of threshold values to determine which signal processing schemes are to be applied. In one embodiment of the invention, each plurality of threshold values to which levels of the frequency band signals are compared, is derived from a speech-shaped spectrum. Additional measures such as amplitude modulation or a signal index may also be employed and compared to corresponding threshold values in the determination.

Claims

1. A process for adaptively processing signals in a hearing aid to improve perception of desired sounds by a user thereof, wherein the hearing aid is adapted to apply one or more of a predefined plurality of signal processing methods to the signals, the process comprising the steps of:

a) receiving an input digital signal, wherein the input digital signal is derived from an input acoustic signal converted from sounds received by the hearing aid;

b) analyzing the input digital signal, wherein at least one level and at least one measure of amplitude modulation is determined from the input digital signal;

c) for each of the plurality of signal processing methods, determining if the respective signal processing method is to be applied to the input digital signal at step d) by performing the substeps of

(i) comparing each level determined at step b) with at least one first threshold value defined for the respective signal processing method, and

(ii) comparing each measure of amplitude modulation determined at step b) with at least one second threshold value defined for the respective signal processing method; and

d) processing the input digital signal to produce an output digital signal, wherein the processing step comprises applying each signal processing method to the input digital signal as determined at step c).

2. The process of claim 1, wherein the predefined plurality of signal processing methods comprises the following signal processing methods:

adaptive microphone directionality, adaptive noise reduction, adaptive real-time feedback cancellation, and adaptive wind noise management.

3. The process of claim 1, wherein step b) comprises determining a broadband, average level of the input digital signal.

4. The process of claim 1, wherein step b) comprises separating the input digital signal into a plurality of frequency band signals and determining a level for each frequency band signal.

5. The process of claim 4, wherein at least one plurality of first threshold values is defined for each of a subset of the plurality of signal processing methods, wherein each plurality of first threshold values is associated with a processing mode of the respective signal processing method of the subset, and wherein substep (i) of step c) includes:

for each signal processing method of the subset, comparing the level for each frequency band signal with a corresponding first threshold value from each plurality of first threshold values defined for the respective signal processing method, in determining if the respective signal processing method is to be applied to the input digital signal in a respective processing mode thereof.

6. The process of claim 5, wherein step d) comprises applying each signal processing method of the subset to the frequency band signals of the input digital signal as determined at step c), and recombining the frequency band signals to produce the output digital signal.

7. The process of claim 5, wherein for each frequency band signal, adaptive microphone directionality can be applied thereto in one of three processing modes comprising an omni-directional mode, a first directional mode, and a second directional mode.

8. The process of claim 5, wherein for each frequency band signal, adaptive wind noise management processing can be applied thereto, wherein adaptive noise reduction is applied to the respective frequency band signal when low level wind noise is detected therein, and wherein adaptive maximum output reduction is applied to frequency band signals when high level wind noise is detected therein.

9. The process of claim 5, wherein at least one plurality of first threshold values for each signal processing method of the subset is derived from a speech-shaped spectrum.

10. The process of claim 1, wherein step b) comprises determining a broadband measure of amplitude modulation from the input digital signal.

11. The process of claim 1, wherein step b) comprises separating the input digital signal into a plurality of frequency band signals and determining a measure of amplitude modulation for each frequency band signal.

12. The process of claim 11, wherein at least one plurality of second threshold values is defined for each of a subset of the plurality of signal processing methods, wherein each plurality of second threshold values is associated with a processing mode of the respective signal processing method of the subset, and wherein substep (ii) of step c) comprises:

for each signal processing method of the subset, comparing the measure of amplitude fluctuation for each frequency band signal with a corresponding second threshold value from each plurality of second threshold values defined for the respective signal processing method, in determining if the respective signal processing method is to be applied to the input digital signal in a respective processing mode thereof.

13. The process of claim 12, wherein at least one plurality of second threshold values for each signal processing method of the subset is derived from a speech-shaped spectrum.

14. The process of claim 1, further comprising the step of modifying the at least one first threshold value using input received from the user.

15. The process of claim 1, further comprising the step of modifying the at least one second threshold value using input received from the user.

16. The process of claim 1, wherein the applying of each signal processing method to the input digital signal at step d) is performed in accordance with a transition scheme selected from the following group:

hard switching; and

soft switching.

17. A digital hearing aid comprising a processing core programmed to perform the steps of the process of claim 1.

18. A process for adaptively processing signals in a hearing aid to improve perception of desired sounds by a user thereof, wherein the hearing aid is adapted to apply one or more of a predefined plurality of signal processing methods to the signals, the process comprising the steps of:

a) receiving an input digital signal, wherein the input digital signal is derived from an input acoustic signal converted from sounds received by the hearing aid;

b) analyzing the input digital signal, wherein at least one level and at least one signal index value is determined from the input digital signal;

c) for each of the plurality of signal processing methods, determining if the respective signal processing method is to be applied to the input digital signal at step d) by performing the substeps of

(i) comparing each level determined at step b) with at least one first threshold value defined for the respective signal processing method, and

(ii) comparing each signal index value determined at step b) with at least one second threshold value defined for the respective signal processing method; and

d) processing the input digital signal to produce an output digital signal, wherein the processing step comprises applying each signal processing method to the input digital signal as determined at step c).

19. The process of claim 18, wherein each signal index value is derived from one or more measures of amplitude modulation, modulation frequency, and time duration derived from the input digital signal.

20. The process of claim 18, wherein the predefined plurality of signal processing methods comprises the following signal processing methods:

adaptive microphone directionality, adaptive noise reduction, adaptive real-time feedback cancellation, and adaptive wind noise management.

21. The process of claim 18, wherein step b) comprises determining a broadband, average level of the input digital signal.

22. The process of claim 18, wherein step b) comprises separating the input digital signal into a plurality of frequency band signals and determining a level for each frequency band signal.

23. The process of claim 22, wherein at least one plurality of first threshold values is defined for each of a subset of the plurality of signal processing methods, wherein each plurality of first threshold values is associated with a processing mode of the respective signal processing method of the subset, and wherein substep (i) of step c) includes:

for each signal processing method of the subset, comparing the level for each frequency band signal with a corresponding first threshold value from each plurality of first threshold values defined for the respective signal processing method, in determining if the respective signal processing method is to be applied to the input digital signal in a respective processing mode thereof.

24. The process of claim 23, wherein step d) comprises applying each signal processing method of the subset to the frequency band signals of the input digital signal as determined at step c), and recombining the frequency band signals to produce the output digital signal.

25. The process of claim 23, wherein for each frequency band signal, adaptive microphone directionality can be applied thereto in one of three processing modes comprising an omni-directional mode, a first directional mode, and a second directional mode.

26. The process of claim 23, wherein for each frequency band signal, adaptive wind noise management processing can be applied thereto, wherein adaptive noise reduction is applied to the respective frequency band signal when low level wind noise is detected therein, and wherein adaptive maximum output reduction is applied to the respective frequency band signal when high level wind noise is detected therein.

27. The process of claim 23, wherein at least one plurality of first threshold values for each signal processing method of the subset is derived from a speech-shaped spectrum.

28. The process of claim 18, wherein step b) comprises determining a broadband signal index value from the input digital signal.

29. The process of claim 18, wherein step b) comprises separating the input digital signal into a plurality of frequency band signals and determining a signal index value for each frequency band signal.

30. The process of claim 29, wherein at least one plurality of second threshold values is defined for each of a subset of the plurality of signal processing methods, wherein each plurality of second threshold values is associated with a processing mode of the respective signal processing method of the subset, and wherein substep (ii) of step c) comprises:

for each signal processing method of the subset, comparing the signal index value for each frequency band signal with a corresponding second threshold value from each plurality of second threshold values defined for the respective signal processing method, in determining if the respective signal processing method is to be applied to the input digital signal in a respective processing mode thereof.

31. The process of claim 30, wherein at least one plurality of second threshold values for each signal processing method of the subset is derived from a speech-shaped spectrum.

32. The process of claim 18, further comprising the step of modifying the at least one first threshold value using input received from the user.

33. The process of claim 18, further comprising the step of modifying the at least one second threshold value using input received from the user.

34. The process of claim 18, wherein the applying of each signal processing method to the input digital signal at step d) is performed in accordance with a transition scheme selected from the following group:

hard switching; and

soft switching.

35. A digital hearing aid comprising a processing core programmed to perform the steps of the process of claim 18.

36. A process for adaptively processing signals in a hearing aid to improve perception of desired sounds by a user thereof, wherein the hearing aid is adapted to apply one or more of a predefined plurality of signal processing methods to the signals, the process comprising the steps of:

a) receiving an input digital signal, wherein the input digital signal is derived from an input acoustic signal converted from sounds received by the hearing aid;

b) analyzing the input digital signal, wherein the input digital signal is separated into a plurality of frequency band signals, and wherein a level for each frequency band signal is determined;

c) for each of a subset of said plurality of signal processing methods, comparing the level for each frequency band signal with a corresponding threshold value from each of at least one plurality of threshold values defined for the respective signal processing method of the subset, wherein each plurality of threshold values is associated with a processing mode of the respective signal processing method of the subset, to determine if the respective signal processing method is to be applied to the input digital signal in a respective processing mode thereof at step d); and

d) processing the input digital signal to produce an output digital signal, wherein the processing step comprises applying each signal processing method of the subset to the frequency band signals of the input digital signal as determined at step c), and recombining the frequency band signals to produce the output digital signal.

37. The process of claim 36, further comprising an additional step of determining whether additional signal processing methods not in said subset are to be applied to the digital signal at step d), and wherein the processing step further comprises applying each additional signal processing method not in said subset to the input digital signal as determined at said additional step.

38. The process of claim 36, wherein the predefined plurality of signal processing methods comprises the following signal processing methods:

adaptive microphone directionality, adaptive noise reduction, adaptive real-time feedback cancellation, and adaptive wind noise management.

39. The process of claim 36, wherein for each frequency band signal, adaptive microphone directionality can be applied thereto in one of three processing modes comprising an omni-directional mode, a first directional mode, and a second directional mode.

40. The process of claim 36, wherein for each frequency band signal, adaptive wind noise management processing can be applied thereto, wherein adaptive noise reduction is applied to the respective frequency band signal when low level wind noise is detected therein, and wherein adaptive maximum output reduction is applied to the respective frequency band signals when high level wind noise is detected therein.

41. The process of claim 36, further comprising determining a broadband, average level of the input digital signal, to be used as an additional threshold value for determining whether one or more of the signal processing methods in the subset are to be applied in the processing step.

42. The process of claim 36, wherein the plurality of threshold values for each signal processing method of the subset is derived from a speech-shaped spectrum.

43. The process of claim 36, further comprising the step of modifying the at least one first threshold value using input received from the user.

44. The process of claim 36, further comprising the step of modifying the at least one second threshold value using input received from the user.

45. The process of claim 36, wherein the applying of each signal processing method to the input digital signal at step d) is performed in accordance with a transition scheme selected from the following group:

hard switching; and

soft switching.

46. A digital hearing aid comprising a processing core programmed to perform the steps of the process of claim 36.