Method for Jointly Optimizing Noise Reduction and Voice Quality in a Mono or Multi-Microphone System

• US 20110257967A1
• Filed: 07/08/2010
• Published: 10/20/2011
• Est. Priority Date: 04/19/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Audience Corporation
• Inventors: Avendano, Carlos, Every, Mark
• Granted Patent: US 8,473,287 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 2021/02087 the noise being separate speech, e.g. cocktail party
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band
• CPC Class Codes: H04R 3/002 Damping circuit arrangements for transducers, e.g. motional feedback circuits

Abstract

The present technology provides adaptive noise reduction of an acoustic signal using a sophisticated level of control to balance the tradeoff between speech loss distortion and noise reduction. The energy level of a noise component in a sub-band signal of the acoustic signal is reduced based on an estimated signal-to-noise ratio of the sub-band signal, and further on an estimated threshold level of speech distortion in the sub-band signal. In embodiments, the energy level of the noise component in the sub-band signal may be reduced to no less than a residual noise target level. Such a target level may be defined as a level at which the noise component ceases to be perceptible.

Claims

1. A method for reducing noise within an acoustic signal, comprising:

receiving an acoustic signal;

separating the acoustic signal into a plurality of sub-band signals; and

applying a reduction value to a sub-band signal in the plurality of sub-band signals to reduce an energy level of a noise component in the sub-band signal, the reduction value based on an estimated signal-to-noise ratio of the sub-band signal, and further based on an estimated threshold level of speech loss distortion in the sub-band signal.

2. The method of claim 1, wherein applying the reduction value comprises performing noise cancellation of the sub-band signal based on the reduction value.

3. The method of claim 1, wherein applying the reduction value comprises multiplying the reduction value to the sub-band signal.

4. The method of claim 2, further comprising multiplying a second reduction value to the sub-band signal to further reduce the energy level of the noise component.

5. The method of claim 1, wherein the energy level of the noise component in the sub-band signal is reduced to no less than a residual noise target level.

6. The method of claim 5, further comprising:

determining a first value for the reduction value based on the estimated signal-to-noise ratio and the estimated threshold level of speech loss distortion; and

determining a second value for the reduction value based on reducing the energy level of the noise component in the sub-band signal to the residual noise target level; and

;

selecting one of the first value and the second value as the reduction value.

7. The method of claim 6, further comprising encoding the separated acoustic signal after applying the reduction value.

8. The method of claim 5, wherein the residual noise target level is below an audible level.

9. The method of claim 5, wherein the second reduction value is unity if the energy level of the noise component in the second sub-band signal is less than the residual noise target level.

10. The method of claim 1, wherein the reduction value is further based on estimated power spectral densities for the noise component and for a speech component in the sub-band signal.

11. A computer readable storage medium having embodied thereon a program, the program being executable by a processor to perform a method for reducing noise within an acoustic signal, the method comprising:

receiving an acoustic signal;

separating the acoustic signal into a plurality of sub-band signals; and

applying a reduction value to a sub-band signal in the plurality of sub-band signals to reduce an energy level of a noise component in the sub-band signal, the reduction value based on an estimated signal-to-noise ratio of the sub-band signal, and further based on an estimated threshold level of speech loss distortion in the sub-band signal.

12. The computer readable storage medium of claim 11, wherein applying the reduction value comprises performing noise cancellation of the sub-band signal based on the reduction value.

13. The computer readable storage medium of claim 11, wherein applying the reduction value comprises multiplying the reduction value to the sub-band signal.

14. The computer readable storage medium of claim 11, wherein the energy level of the noise component in the sub-band signal is reduced to no less than a residual noise target level.

15. The computer readable storage medium of claim 14, further comprising:

determining a first value for the reduction value based on the estimated signal-to-noise ratio and the estimated threshold level of speech loss distortion;

determining a second value for the reduction value based on reducing the energy level of the noise component in the sub-band signal to the residual noise target level; and

;

selecting one of the first value and the second value as the reduction value.

16. The computer readable storage medium of claim 11, further comprising multiplying a second reduction value to the sub-band signal to further reduce the energy level of the noise component.

17. The computer readable storage medium of claim 14, wherein the residual noise target level is below an audible level.

18. The computer readable storage medium of claim 14, wherein the second reduction value is unity if the energy level of the noise component in the second sub-band signal is less than the residual noise target level.

19. A system for reducing noise within an acoustic signal, comprising:

a frequency analysis module stored in memory and executed by a processor to receive an acoustic signal and separate the acoustic signal into a plurality of sub-band signals; and

a noise reduction module stored in memory and executed by a processor to apply a reduction value to a sub-band signal in the plurality of sub-band signals to reduce an energy level of a noise component in the sub-band signal, the reduction value based on an estimated signal-to-noise ratio of the sub-band signal, and further based on an estimated threshold level of speech loss distortion in the sub-band signal.

20. The system of claim 19, wherein the noise reduction module performs noise cancellation of the sub-band signal based on the reduction value.

21. The system of claim 19, wherein the noise reduction module multiplies the reduction value to the sub-band signal.

22. The system of claim 19, wherein the energy level of the noise component in the sub-band signal is reduced to no less than a residual noise target level.

23. The system of claim 19, wherein the reduction value is further based on input received via an application program interface for the noise reduction module.