Active noise cancellation in hearing devices

• US 8,229,127 B2
• Filed: 07/15/2008
• Issued: 07/24/2012
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Oticon A/S (William Demant Fonden)
• Original Assignee: Oticon A/S (William Demant Fonden)
• Inventors: Rasmussen, Karsten Bo, Jørgensen, Ivan, Petersen, Svend Oscar
• Primary Examiner(s): LUKS, JEREMY AUSTIN
• Application Number:
  US12/219,063
• Publication Number:
  US 20090041260A1
• Time in Patent Office: 1,470 Days
• Field of Search: 381/71.6, 381/312, 381/317, 381/318
• US Class Current: 381/71.6
• CPC Class Codes: G10K 11/17819 between the output signals and the reference signals, e.g. to prevent howling
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 11/17875 using an error signal without a reference signal, e.g. pure feedback
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: H04R 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 25/453 electronically
• CPC Class Codes: H04R 25/505 using digital signal processing
• CPC Class Codes: H04R 25/554 using a wireless connection, e.g. between microphone and amplifier or using Tcoils

Abstract

Disclosed is a hearing device system comprising at least one hearing aid circuitry and at least one active noise cancellation unit, the at least one hearing aid circuitry comprises at least one input transducer adapted to convert a first audio signal to an electric audio signal; a signal processor connected to the at least one input transducer and adapted to process said electric audio signal by at least partially correcting for a hearing loss of a user; an output transducer adapted to generate from at least said processed electric audio signal a sound pressure in an ear canal of the user, whereby the generated sound pressure is at least partially corrected for the hearing loss of the user; the at least one active noise cancellation unit being adapted to provide an active noise cancellation signal adapted to perform active noise cancellation of an acoustical signal entering the ear canal in addition to said generated sound pressure, wherein the hearing device system further comprises a combiner unit adapted to combine the processed electric audio signal with the active noise cancellation signal, to obtain a combined signal and to provide the combined signal to the output transducer.

Claims

1. A hearing device system, comprising:

at least one hearing aid circuitry including

at least one input transducer adapted to convert a first audio signal to an electric audio signal,

a signal processor connected to the at least one input transducer and configured to process said electric audio signal by at least partially correcting for a hearing loss of a user, thereby generating a processed electric audio signal, and

an output transducer configured to generate from at least said processed electric audio signal a sound pressure in an ear canal of the user, wherein the generated sound pressure is at least partially corrected for the hearing loss of the user;

at least one active noise cancellation unit configured to cancel an acoustic signal bypassing the hearing device positioned in the ear canal by providing an active noise cancellation signal, the at least one active noise cancellation unit including an active noise cancellation filter;

a feed-back cancellation unit configured to estimate an acoustical feedback path from the output transducer to the at least one input transducer and to adjust filter characteristics of the active noise cancellation filter in the at least one active noise cancellation unit; and

a combiner unit configured to combine the processed electric audio signal with the active noise cancellation signal, to obtain a combined signal and to provide the combined signal to the output transducer.

2. A hearing device system according to claim 1, wherein the hearing device system further comprises an audio streaming control unit adapted to receive a second audio signal from an audio streaming device.

3. A hearing device system according to claim 2, wherein the combiner unit is further adapted to combine the second audio signal with the active noise cancellation signal, to obtain a combined signal and to provide the combined signal to the output transducer.

4. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit further comprises an output automatic gain control.

5. A hearing device system according to claim 1, wherein the hearing device system further comprises a pulse width modulation unit adapted to perform pulse width modulation of the combined signal.

6. A hearing device system according to claim 1, wherein the hearing device system further comprises a pulse density modulation unit adapted to perform pulse density modulation of the processed electric audio signal.

7. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit is analogue.

8. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit is digital.

9. A hearing device system according to claim 2, wherein the audio streaming device is digital.

10. A hearing device system according to claim 2, wherein the audio streaming device is analogue.

11. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit is a feed-forward type active noise cancellation unit, where noise cancellation is based on a signal from the at least one input transducer.

12. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit is a feedback type active noise cancellation unit, where noise cancellation is based on a second input transducer adapted to convert a second audio signal from residual space.

13. A hearing device system according to claim 1, wherein the at least one active noise cancellation unit is a combination of feed-forward-type and feedback type active noise cancellation unit.

14. A hearing device system according to claim 2, wherein the hearing device system is wirelessly connectable to the audio streaming device.

15. A hearing device system according to claim 2, wherein the hearing device system is wire-connectable to the audio streaming device.

16. The hearing device system according to claim 1, further comprising:

a second input transducer configured to convert a second audio signal to a second electric audio signal, the second input transducer having directional sensitivity pointed toward ambient space surrounding the hearing device, wherein

the at least one active noise cancellation unit is configured to perform active noise cancellation based on the second electric audio signal.

17. The hearing device system according to claim 1, wherein

the acoustic signal bypassing the hearing device passes through a void between the hearing device and a wall of the ear canal.

18. The hearing device system according to claim 1, wherein

the acoustic signal bypassing the hearing device passes through a vent of the hearing device.

19. A method of improving noise cancellation in a hearing device system, comprising:

converting a first audio signal to an electric audio signal by an input transducer;

processing the electric audio signal by at least partially correcting for a hearing loss of a user by a signal processor;

generating from at least said processed electric audio signal a sound pressure in an ear canal of the user by an output transducer, wherein the generated sound pressure is at least partially corrected for the hearing loss of the user;

providing an active noise cancellation signal adapted to perform active noise cancellation of an acoustical signal bypassing the hearing device positioned in the ear canal of the user by at least one active noise cancellation unit including an active noise cancellation filter;

estimating an acoustical feedback path from the output transducer to the input transducer by a feed-back cancellation unit;

adjusting filter characteristics of the active noise cancellation filter in the at least one active noise cancellation unit by the feed-back cancellation unit; and

combining the processed electric audio signal with the active noise cancellation signal by a combiner unit to obtain a combined signal and providing the combined signal to the output transducer.