Wireless telephone having multiple microphones

• US 20060133621A1
• Filed: 12/22/2004
• Published: 06/22/2006
• Est. Priority Date: 12/22/2004
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Bennett, James, Chen, Juin-Hwey
• Application Number:
  US11/018,921
• Publication Number:
  US 20060133621A1
• Time in Patent Office: Days
• US Class Current: 381/92
• 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 21/0208 Noise filtering
• CPC Class Codes: H03G 3/32 the control being dependent upon ambient noise level or sound level
• CPC Class Codes: H04M 1/6008 in the transmitter circuit

Abstract

The present invention is directed to a wireless telephone having a first microphone and a second microphone and a method for processing audio signal in a wireless telephone having a first microphone and a second microphone. The wireless telephone includes a first microphone, a second microphone, and a signal processor. The first microphone outputs a first audio signal, the first audio signal comprising a voice component and a background noise component. The second microphone outputs a second audio signal. The signal processor increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

Claims

1. A wireless telephone, comprising:

a first microphone that outputs a first audio signal, the first audio signal comprising a voice component and a background noise component;

a second microphone that outputs a second audio signal; and

a signal processor that increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

2. The wireless telephone of claim 1, wherein the first microphone is mounted on a first portion of the wireless telephone and the second microphone is mounted on a second portion of the wireless telephone such that the first microphone is closer to the mouth of a user than the second microphone during regular use of the wireless telephone.

3. The wireless telephone of claim 1, wherein the signal processor comprises a background noise cancellation module that receives the first and second audio signals and cancels at least a portion of the background noise component of the first audio signal based on the content of the second audio signal to produce the third audio signal.

4. The wireless telephone of claim 3, wherein the background noise cancellation module comprises:

an adaptive filter that filters the second audio signal; and

an adder that adds the filtered second audio signal to the first audio signal, thereby canceling at least a portion of the background noise component of the first audio signal.

5. The wireless telephone of claim 3, further comprising:

a first analog-to-digital (A/D) converter connected to the first microphone that converts the first audio signal from an analog form to a digital form prior to receipt of the first audio signal by the background noise cancellation module; and

a second A/D converter connected to the second microphone that converts the second audio signal from an analog form to a digital form prior to receipt of the second audio signal by the background noise cancellation module.

6. The wireless telephone of claim 5, wherein the first and second A/D converters sample the respective first and second audio signals at a first sampling rate before providing the first and second audio signals to the background noise cancellation module;

and

wherein the background noise cancellation module includes a downsampler that down samples the third audio signal to a second sampling rate, wherein the second sampling rate is lower than the first sampling rate.

7. The wireless telephone of claim 3, wherein the signal processor further comprises a noise suppressor that receives the second and third audio signals and suppresses at least a portion of a residual background noise component of the third audio signal based on the content of the second audio signal and the third audio signal to produce a fourth audio signal.

8. The wireless telephone of claim 7, wherein the noise suppressor suppresses at least a portion of the residual background noise component by adapting a frequency spectrum corresponding to the third audio signal.

9. The wireless telephone of claim 3, further comprising:

an adaptive filter that filters the third audio signal to produce a fourth audio signal;

an adder that adds the second audio signal to the fourth audio signal thereby canceling at least a portion of a voice component from the second audio signal to produce a fifth audio signal; and

a noise suppressor that receives the third audio signal and the fifth audio signal and suppresses at least a portion of a residual background noise component of the third audio signal based on the content of the third audio signal and the fifth audio signal to produce a sixth audio signal.

10. The wireless telephone of claim 1, wherein the signal processor comprises a noise suppressor that receives the first and second audio signals and suppresses at least a portion of the background noise component of the first audio signal based on the content of the first audio signal and the second audio signal to produce the third audio signal.

11. The wireless telephone of claim 1, further comprising:

a voice activity detector (VAD) that receives the second and third audio signals and detects time intervals in which a voice component is present in the third audio signal based on the content of the second audio signal and the third audio signal.

12. The wireless telephone of claim 11, wherein the VAD provides input to a transmitter relating to the time intervals in which a voice component is present in the third audio signal;

and

wherein the transmitter selectively transmits the third audio signal to another telephone responsive to the input.

13. The wireless telephone of claim 11, wherein the VAD detects the time intervals by monitoring an energy ratio of the second audio signal and the third audio signal.

14. A method for processing audio signals in a wireless telephone having a first microphone and a second microphone, comprising:

outputting a first audio signal from the first microphone, the first audio signal comprising a voice component and a background noise component;

outputting a second audio signal from the second microphone; and

increasing a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

15. The method of claim 14, wherein the increasing step comprises:

canceling at least a portion of the background noise component of the first audio signal based on the content of the second audio signal to produce the third audio signal.

16. The method of claim 15, wherein canceling at least a portion of the background noise component of the first audio signal based on the content of the second audio signal comprises:

filtering the second audio signal using an adaptive filter; and

adding the filtered second audio signal to the first audio signal, thereby canceling at least a portion of the background noise component of the first audio signal.

17. The method of claim 15, further comprising:

converting each of the first and second audio signals from an analog form to a digital form prior to the canceling step.

18. The method of claim 17, wherein converting each of the first and second audio signals from an analog form to a digital form comprises sampling the first and second audio signals at a first sampling rate, and wherein the method further comprises downsampling the third audio signal to a second sampling rate, wherein the second sampling rate is lower than the first sampling rate.

19. The method of claim 14, wherein the increasing step comprises:

suppressing at least a portion of the background noise component of the first audio signal based on the content of the first audio signal and the second audio signal to produce the third audio signal.

20. The method of claim 15, further comprising:

suppressing at least a portion of a residual background noise component of the third audio signal based on the content of the second audio signal and the third audio signal to produce a fourth audio signal.

21. The method of claim 20, wherein the suppressing step comprises suppressing at least a portion of the residual background noise component by adapting a frequency spectrum corresponding to the third audio signal.

22. The method of claim 14, further comprising:

detecting time intervals in which a voice component is present in the third audio signal based on the content of the second audio signal and the third audio signal.

23. The method of claim 22, further comprising:

selectively transmitting the third audio signal to another telephone during the time intervals in which a voice component is present in the third audio signal.

24. A corded telephone, comprising:

a first microphone that outputs a first audio signal, the first audio signal comprising a voice component and a background noise component;

a second microphone that outputs a second audio signal; and

a signal processor that increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

25. A headset telephone, comprising:

a headset having a first microphone that outputs a first audio signal, the first audio signal comprising a voice component and a background noise component; and

a handset having a second microphone that outputs a second audio signal and a signal processor that receives the first and the second audio signals and increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

26. A headset telephone, comprising:

a headset having a first microphone that outputs a first audio signal, the first audio signal comprising a voice component and a background noise component, and the headset having a second microphone that outputs a second audio signal; and

a handset having a signal processor that receives the first and the second audio signals and increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

27. A headset telephone, comprising:

a headset having a first microphone that outputs a first audio signal, the first audio signal comprising a voice component and a background noise component, and the headset having a second microphone that outputs a second audio signal; and

the headset having a signal processor that receives the first and the second audio signals and increases a ratio of the voice component to the noise component of the first audio signal based on the content of at least one of the first audio signal and the second audio signal to produce a third audio signal.

28. The telephone of claim 27, wherein the headset is a BLUETOOTH™

headset.