Dual microphone noise reduction for headset application

• US 20080037801A1
• Filed: 08/10/2006
• Published: 02/14/2008
• Est. Priority Date: 08/10/2006
• Status: Active Grant

• Current Assignee: Qualcomm technologies international, ltd. (Qualcomm, Inc.)
• Original Assignee: Cambridge Silicon Radio Limited (Qualcomm, Inc.)
• Inventors: Yen, Kuan-Chieh, Alves, Rogerio G.
• Granted Patent: US 7,773,759 B2
• Time in Patent Office: Days
• US Class Current: 381/71.6
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 3/02 for preventing acoustic reaction , i.e. acoustic oscillatory feedback specially adapted for hearing aids H04R25/453
• CPC Class Codes: H04R 3/04 for correcting frequency response

Abstract

Improved vocal signals are obtained in headsets and similar devices by including a microphone inside a chamber formed at least in part by the wearer'"'"'s ear. This second microphone provides a reduced noise input signal. The reduced noise signal is corrected by input from another microphone, located outside the chamber. This correction can include echo cancellation, spectral shaping, frequency extension, and the like.

Claims

1. A system comprising:

an ear portion forming a chamber with at least a portion of an ear, the chamber reducing ambient noise from outside the chamber;

a first microphone outside the chamber positioned to pick up vocal sound from a wearer of the system, the first microphone generating a first signal;

a speaker providing sound to the chamber;

a second microphone disposed within the chamber generating a second signal;

an echo reducer reducing the effects of the speaker signal in the second signal; and

a dynamic equalizer adjusting the frequency spectrum of the second signal based on the first signal to produce a filtered signal.

2. The system of claim 1 further comprising a first noise reducer reducing noise in the first signal.

3. The system of claim 1 wherein an output signal is produced by combining low frequency output based on the filtered signal with high frequency output based on the first signal.

4. The system of claim 3 wherein the echo reducer is a first echo reducer, the system further comprising a second echo reducer reducing the effects of the speaker signal in the high frequency output.

5. The system of claim 1 further comprising a double talk detector.

6. The system of claim 1 further comprising:

a first analysis filter in communication with the first microphone, the first analysis filter generating a first analysis filter output comprising a frequency domain representation of the first signal;

a second analysis filter in communication with the second microphone, the second analysis filter generating a second analysis filter output comprising a frequency domain representation of the second signal; and

a synthesis filter generating a time domain representation of the filtered signal.

7. A method of generating a reduced noise vocal signal in a system having a first microphone and an earpiece, the earpiece forming a chamber with an ear when the earpiece is in contact with the ear, the earpiece including a speaker and a second microphone, the second microphone operative to sense sound in the chamber, the method comprising:

decomposing output of the first microphone into a first subbanded signal;

decomposing output of the second microphone into a second subbanded signal;

generating an equalized signal by equalizing the second subbanded signal to the first subbanded signal; and

producing the reduced noise vocal signal based on the equalized signal and on the first subbanded signal.

8. The method of claim 7 wherein the reduced noise signal is based on low frequency components of the equalized signal and on high frequency components of the first subbanded signal.

9. The method of claim 8 further comprising canceling echos in the high frequency components of the first subbanded signal.

10. The method of claim 7 further comprising canceling echos in the second subbanded signal prior to generating the equalized signal.

11. The method of claim 10 wherein canceling echos is based on a subbanded input to the speaker.

12. The method of claim 7 wherein the equalized signal is generated based on a plurality of low frequency subbands of the first subbanded signal.

13. The method of claim 7 further comprising reducing noise in the equalized signal.

14. The method of claim 7 further comprising reducing noise in the first subbanded signal.

15. A method of generating a reduced noise vocal signal in a system having a first microphone and an earpiece, the earpiece forming a chamber with an ear when the earpiece is in contact with the ear, the earpiece including a speaker and a second microphone, the second microphone operative to sense sound inside the chamber to produce a second signal and the first microphone operative to sense sound outside the chamber to produce a first signal, the method comprising:

filtering noise from the first signal to produce a first filtered signal;

generating an equalized signal by equalizing the second signal to the first filtered signal;

filtering noise from the equalized signal to produce a second filtered signal; and

generating the reduced noise vocal signal based on the first filtered signal and the second filtered signal.

16. The method of claim 15 further comprising generating a first low frequency signal and a first high frequency signal, the first low frequency signal having high frequency components of the first filtered signal removed and the first high frequency signal having low frequency components of the first filtered signal removed.

17. The method of claim 16 wherein the equalized signal is based on the first low frequency signal.

18. The method of claim 16 wherein the equalized signal is based on a difference between the first low frequency signal and the second filtered signal.

19. The method of claim 16 wherein the reduced noise signal is generated by combining the second filtered signal and the first high frequency signal.

20. The method of claim 16 further comprising canceling echos in the first high frequency signal.

21. The method of claim 15 further comprising canceling echos in the second signal.

22. The method of claim 15 further comprising using voice detection to selectively enable outputting the reduced noise vocal signal.

23. The method of claim 15 further comprising reducing noise in the second signal prior to equalizing the second signal.

24. A system for generating a reduced noise vocal signal based on speech spoken by a user, the user using an ear portion forming a chamber with at least a portion of an ear of the user, the chamber reducing ambient noise from outside the chamber, the chamber including a speaker providing sound to the ear of the user, the user also using a first microphone outside the chamber positioned to pick up the speech spoken by the user, the first microphone generating a first signal based on the speech spoken by the user, the system comprising:

a second microphone disposed within the chamber generating a second signal, the second signal based on the speech spoken by the user; and

audio processing circuitry in communication with the first microphone and the second microphone, the audio processing circuitry operative to generate the reduced noise vocal signal by processing the second signal based on the first signal.