Noise error amplitude reduction

• US 8,229,126 B2
• Filed: 03/13/2009
• Issued: 07/24/2012
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Chamberlain, Mark, Keane, Anthony Richard Alan
• Primary Examiner(s): Warren, David S.
• Application Number:
  US12/403,646
• Publication Number:
  US 20100232616A1
• Time in Patent Office: 1,229 Days
• Field of Search: 381/57, 381/71.1, 381/71.7, 381/71.11
• US Class Current: 381/71.1
• 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

Abstract

Systems (200) and methods (100) for noise error amplitude reduction. The methods involve configuring a first microphone system (202) and a second microphone system (302) so that far field sound originating in a far field environment relative to the first and second microphone systems produces a difference in sound signal amplitude at the first and second microphone systems. The difference has a known range of values. The methods involve (128) dynamically identifying the far field sound based on the difference. The methods also involve (130, 132, 134) automatically reducing substantially to zero a gain applied to the far field sound responsive to the identifying step.

Claims

1. A method for noise reduction, comprising:

receiving a primary mixed input signal at a first microphone system of a communication device and a second mixed input signal at a second microphone system of said communication device, said first and second microphone systems disposed at locations on said communication device so that far field sound originating in a far field environment relative to said first and second microphone systems produces a first difference in sound signal amplitude at said first and second microphone systems;

dynamically identifying a first far field sound component contained in said primary mixed input signal and a second far field sound component contained in said secondary mixed input signal based on said first difference, said first far field sound component having first magnitude values and said second far field sound component having second magnitude values;

generating adjusted magnitude values by setting said second magnitude values equal to said first magnitude values;

determining a plurality of gain values using said first magnitude values and said adjusted magnitude values; and

automatically reducing said first far field sound component using said plurality of gain values.

2. The method according to claim 1, wherein said identifying step comprises determining if said first difference falls within a predefined range of values.

3. The method according to claim 1, wherein said reducing step comprises dynamically modifying said sound signal amplitude level for at least one first component of said far field sound detected by said first microphone system.

4. The method according to claim 3, wherein said component is a frequency component.

5. The method according to claim 1, wherein at least one of said plurality of gain values is determined based on a comparison of a relative sound signal amplitude level for said first far field sound component and said second far field sound component.

6. The method according to claim 1, wherein at least one of said plurality of gain values is selected based on a ratio of said sound signal amplitude level for said first far field sound component and said second far field sound component.

7. The method according to claim 6, further comprising setting at least one of said plurality of gain values to zero if said sound signal amplitude level for said first component and said second component are approximately equal.

8. The method according to claim 1, further comprising configuring said first microphone system and said second microphone system so that near field sound originating in a near field environment relative to said first and second microphone systems produces a second difference in said sound signal amplitude at said first and second microphone systems, said second difference different than said first difference.

9. The method according to claim 1, wherein said far field environment comprises locations at least three feet distant from said first and second microphone systems.

10. The method according to claim 1, further comprising selecting at least one parameter of a first microphone associated with said first microphone system and a second microphone associated with said second microphone system.

11. The method according to claim 10, wherein said parameter is selected from the group consisting of a distance between said first and second microphones, a microphone field pattern, a microphone orientation, and acoustic feed system.

12. A noise error amplitude reduction (“

NEAR”

) system, comprising;

a first microphone system configured to produce a primary mixed input signal;

a second microphone system configured to produce a secondary mixed input signal, where said first and second microphone systems are disposed at locations on a communication device so that far field sound originating in a far field environment relative to said first and second microphone systems produces a first difference in sound signal amplitude at said first and second microphone systems;

at least one signal processing device configured to

dynamically identify a first far field sound component of said primary mixed input signal and a second far field sound component of said secondary mixed input signal based on said first difference, said first far field sound component having first magnitude values and said second far field sound component having second magnitude values,

generating adjusted magnitude values by setting said second magnitude values equal to said first magnitude values,

computing a plurality of gain values using said first magnitude values and said adjusted magnitude values, and

automatically reduce said first far field sound component using said plurality of gain values.

13. The noise error amplitude reduction system according to claim 12, wherein said far field sound is identified by determining if said first difference falls within a predefined range of values.

14. The noise error amplitude reduction system according to claim 12, wherein said signal processing device is further configured to dynamically modify said sound signal amplitude level for at least one first component of said far field sound detected by said first microphone system.

15. The noise error amplitude reduction system according to claim 12, wherein at least one of said gain values is determined based on a comparison of a relative sound signal amplitude level for said first far field sound component and said second far field sound component.

16. The noise error amplitude reduction system according to claim 12 , wherein said signal processing device is further configured to select at least one of said plurality of gain values based on a ratio of sound signal amplitude levels for said first far field sound component and said second far field component.

17. The noise error amplitude reduction system according to claim 16, wherein said signal processing device is further configured to set at least one of said plurality of gain values to zero if said sound signal amplitude levels for said first far field sound component and said second far field sound component are approximately equal.

18. The noise error amplitude reduction system according to claim 12, wherein said first microphone system and said second microphone system are configured so that near field sound originating in a near field environment relative to said first and second microphone systems produces a second difference in said sound signal amplitude at said first and second microphone systems, said second difference different than said first difference.

19. The noise error amplitude reduction system according to claim 12, wherein said far field environment comprises locations at least three feet distant from said first and second microphone systems.

20. The noise error amplitude reduction system according to claim 12, wherein said first and second microphone systems are configured by selecting at least one parameter of a first microphone associated with said first microphone system and a second microphone associated with said second microphone system.

21. The noise error amplitude reduction system according to claim 20, wherein said parameter is selected from the group consisting of a distance between said first and second microphone, a microphone field pattern, a microphone orientation, and acoustic feed system.