Ambient noise compensation system robust to high excitation noise

• US 9,123,352 B2
• Filed: 11/14/2012
• Issued: 09/01/2015
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: 2236008 Ontario Inc. (Blackberry Limited)
• Inventors: Hetherington, Phillip A.
• Primary Examiner(s): PULLIAS, JESSE SCOTT
• Application Number:
  US13/676,821
• Publication Number:
  US 20130070931A1
• Time in Patent Office: 1,021 Days
• Field of Search: 704/225, 704/226, 704/E21.002, 704/E21.007
• US Class Current: 1/1
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10

Abstract

A speech enhancement system controls the gain of an excitation signal to prevent uncontrolled gain adjustments. The system includes a first device that converts sound waves into operational signals. An ambient noise estimator is linked to the first device and an echo canceller. The ambient noise estimator estimates how loud a background noise would be near the first device before or after an echo cancellation. The system then compares the ambient noise estimate to a current ambient noise estimate near the first device to control a gain of an excitation signal.

Claims

1. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate; and

controlling a gain of the excitation signal based on a result of the comparison;

where the estimate of the loudness of the background noise comprises estimating a coupling factor value that represents a ratio of the excitation signal magnitude to an error signal after a filtering stage of an echo canceller.

2. The method of claim 1, where the step of estimating the background noise comprises estimating the background noise when only the excitation signal is played over the speaker.

3. The method of claim 2, where the coupling factor comprises an enclosure coupling factor that represents a ratio of excitation signal magnitude to microphone signal magnitude when only the excitation signal is playing out into an enclosure.

4. The method of claim 2, where the coupling factor comprises an error coupling factor that represents the ratio of the excitation signal magnitude to an error signal magnitude after a linear filtering device stage of the echo canceller that processes signals captured by the microphone.

6. The method of claim 1, where the step of controlling the gain comprises modifying the gain to be applied to the excitation signal prior to the excitation signal being played over the speaker into the acoustic environment.

7. The method of claim 1, where the excitation signal comprises downlink noise from a far end of a communication channel.

9. The method of claim 1, further comprising:

accessing computer-readable noise compensation instructions from a computer memory; and

executing the computer-readable noise compensation instructions by a processor to execute the steps of performing the comparison and controlling the gain of the excitation signal.

5. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate;

determining that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level; and

reducing the gain of the excitation signal or stopping further increases in the gain of the excitation signal in response to the determination that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level.

8. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate;

controlling a gain of the excitation signal based on a result of the comparison;

determining that the background noise resulting from the excitation signal noise is too high based on the result of the comparison;

setting a flag or status marker in response to the determination that the background noise resulting from the excitation signal noise is too high; and

controlling the gain to be applied to the excitation signal while the flag or status marker is set.

10. A noise compensation system, comprising:

a computer memory that stores computer-readable noise compensation instructions; and

a processor configured to execute the computer-readable noise compensation instructions, where execution of the computer-readable noise compensation instructions causes the processor to;

estimate a level of background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generate an ambient noise estimate associated with the acoustic environment;

perform a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate; and

control a gain of the excitation signal based on a result of the comparison;

where the estimate of the level of background noise comprises estimating a coupling factor value that represents a ratio of the excitation signal magnitude to an error signal after a filtering stage of an echo canceller.

11. The system of claim 10, where the computer-readable noise compensation instructions that cause the processor to estimate the background noise comprise instructions that cause the processor to estimate the background noise when only the excitation signal is played over the speaker.

12. The system of claim 11, where the coupling factor comprises an enclosure coupling factor that represents a ratio of the excitation signal magnitude to the microphone signal magnitude when only the excitation signal is playing out into an enclosure.

13. The system of claim 11, where the coupling factor comprises an error coupling factor that represents a ratio of the excitation signal magnitude to an error signal magnitude after a linear filtering device stage of the echo canceller that processes signals captured by the microphone.

14. The system of claim 10, where the computer-readable noise compensation instructions that cause the processor to control the gain comprise instructions that cause the processor to:

determine that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level; and

reduce the gain of the excitation signal or stopping further increases in the gain of the excitation signal in response to the determination that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level.

15. The system of claim 10, where the computer-readable noise compensation instructions that cause the processor to control the gain comprise instructions that cause the processor to modify the gain to be applied to the excitation signal prior to the excitation signal being played over the speaker into the acoustic environment.

16. The system of claim 10, where the excitation signal comprises downlink noise from a far end of a communication channel.

17. A noise compensation system, comprising:

a computer memory that stores computer-readable noise compensation instructions; and

a processor configured to execute the computer-readable noise compensation instructions, where execution of the computer-readable noise compensation instructions causes the processor to;

estimate how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generate an ambient noise estimate associated with the acoustic environment;

perform a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate;

control a gain of the excitation signal based on a result of the comparison;

determine that the background noise resulting from the excitation signal noise is too high based on the result of the comparison;

set a flag or status marker in response to the determination that the background noise resulting from the excitation signal noise is too high; and

control the gain to be applied to the excitation signal while the flag or status marker is set.

18. A non-transitory computer-readable medium with instructions stored thereon, where the instructions are executable by a processor to cause the processor to perform the steps of:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate; and

controlling a gain of the excitation signal based on a result of the comparison;

where the estimate of the level of background noise comprises estimating a coupling factor value that represents a ratio of the excitation signal magnitude to the error signal after the filtering stage of an echo canceller.

19. The non-transitory computer-readable medium of claim 18, where the instructions executable by the processor to cause the processor to control the gain comprise instructions executable by the processor to cause the processor to perform the steps of:

determining that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level; and

reducing the gain of the excitation signal or stopping further increases in the gain of the excitation signal in response to the determination that the background noise estimate associated with the excitation signal is higher than the ambient noise estimate by a predetermined level.

20. The non-transitory computer-readable medium of claim 18, where the instructions executable by the processor to cause the processor to estimate the background noise comprise instructions executable by the processor to cause the processor to perform the step of estimating the background noise when only the excitation signal is played over the speaker.

21. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment based on a magnitude of the excitation signal and an error signal after a filtering stage;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate; and

controlling a gain of the excitation signal based on a result of the comparison;

where the estimate of the level of background noise comprises estimating a coupling factor value that represents a ratio of the excitation signal magnitude to the error signal after the filtering stage of an echo canceller.

22. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate;

controlling a gain of the excitation signal based on a result of the comparison by reducing the gain of the excitation signal in response to a determination that an estimate from the excitation signal and a coupling factor is more than the background noise estimate by a second threshold.

23. A noise compensation method, comprising:

estimating how loud a background noise resulting from an excitation signal played over a speaker into an acoustic environment would be in a signal captured by a microphone in the acoustic environment;

generating an ambient noise estimate associated with the acoustic environment;

performing a comparison between the background noise estimate resulting from the excitation signal and a threshold based on the ambient noise estimate;

controlling a gain of the excitation signal based on a result of the comparison by stopping further increases in the gain of the excitation signal in response to a determination that an estimate from the excitation signal and a coupling factor is more than the background noise estimate by a second threshold.