Detecting nonlinear amplitude processing

• US 9,449,593 B2
• Filed: 02/07/2014
• Issued: 09/20/2016
• Est. Priority Date: 11/29/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Ekman, Lars Anders, de Vicente Pea, Jesus
• Primary Examiner(s): Bernardi, Brenda
• Application Number:
  US14/175,794
• Publication Number:
  US 20150154977A1
• Time in Patent Office: 956 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G10K 11/175 using interference effects; Masking sound
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 25/03 characterised by the type of extracted parameters
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23

Abstract

Disclosed is a computer system comprising an audio processing module, an echo cancellation module and a control module. The audio processing module is configured to process an audio signal and output the processed audio signal to e.g. a speaker (or similar) of the system. The echo cancellation module is configured to cancel echo from an audio signal received via e.g. a microphone (or similar) of the system. The control module is configured to detect a condition indicative of nonlinear amplitude processing by the audio processing module and control said echo cancellation by the echo cancellation module based on the detected condition.

Claims

1. A computer system comprising:

an audio processing module configured to process an audio signal and output the processed audio signal to an audio output device of the system;

an echo cancellation module configured to cancel echo from a received audio signal received via an audio input device of the system; and

a control module configured to detect a degree of nonlinear amplitude processing by the audio processing module and control said echo cancellation by applying more or less aggressive echo cancellation settings by the echo cancellation module based on the detected degree.

2. A computer system according to claim 1, wherein said control module is configured to, for each of the audio signal and the received audio signal, determine a parameter of an amplitude distribution for that audio signal, said detection comprising comparing the determined parameters for each distribution.

3. A computer system according to claim 2, wherein said control module is configured to determine said distributions over a range of values corresponding to signal amplitudes of the respective signals.

4. A computer system according to claim 3, wherein said values are magnitudes of the respective signal amplitudes, the control module being operable to calculate said magnitudes.

5. A computer system according to claim 2, wherein said distributions are histograms for the respective audio signals.

6. A computer system according to claim 5, wherein each of said histograms for the respective audio signals comprises a plurality of bins, each bin being a range of magnitudes of signal amplitudes of that audio signal.

7. A computer system according to claim 6, wherein each of said histograms has a first bin, a second bin for amplitude values greater than the first bin, and at least a third bin for amplitude values greater than the second bin, and determining each of said distribution parameters comprises, for each of said histograms, comparing the second bin of that histogram to at least the third bin of that histogram.

8. A computer system according to claim 2, wherein determining each of said respective distribution parameters for the respective distributions comprises determining a weight parameter by comparing an upper portion of that distribution to a lower portion of that distribution, said detection comprising comparing the determined weight parameters for the respective distributions.

9. A computer system according to claim 2, wherein determining each of said respective distribution parameters for the respective distributions comprises determining a percentile for that distribution, said detection comprising comparing the determined percentiles for the respective distributions.

10. A computer system according to claim 2 further comprising a modelling module configured to calculate a linear model of an echo path of the received signal, said echo cancellation by the echo cancellation module being based on the linear model.

11. A computer system according to claim 2, wherein the control module is configured to control the echo cancellation module to prevent echo leaks due to nonlinearities in an echo path of the received signal introduced by said nonlinear amplitude processing by the audio processing module.

12. A computer system according to claim 1, wherein the control module is configured to determine respective histograms for values corresponding to respective signal amplitudes of the audio signal and the received audio signal respectively, said detection comprising comparing those histograms.

13. A computer system according to claim 1, wherein said detection comprises comparing the audio signal and the received audio signal.

14. A computer system according to claim 1, wherein the control module is configured to normalize one or more of the audio signal and the received audio signal, said detection being based on the normalized audio signals.

15. A computer system according to claim 14, wherein said control module is configured to, for each of the audio signal and the received audio signal, determine a parameter of an amplitude distribution for that audio signal, said detection comprising comparing the determined parameters for each distribution, wherein said distributions are distributions for the respective normalized signals.

16. A computer system according to claim 1, wherein said nonlinear amplitude processing by the audio processing module comprises dynamic range compression.

17. At least one computer readable storage medium storing code which, when executed on one or more processors of a computer system comprising an audio processing module configured to process an audio signal and output the processed audio signal to an audio output device of the system, causes the one or more processors to:

cancel echo from a received audio signal received via an audio input device of the system;

detect a degree of nonlinear amplitude processing by the audio processing module; and

control said echo cancellation more or less aggressively based on the detected degree, more aggressive echo cancellation being applied when the detected degree is higher and less aggressive echo cancellation being applied when the detected degree is lower.

18. At least one computer readable storage medium according to claim 17, wherein said code further causes the one or more processors to, for each of the audio signal and the received audio signal, determine a parameter of an amplitude distribution for that audio signal, said detection comprising comparing the determined parameters for each distribution.

19. A computer device comprising:

one or more processors configured to;

for each of first and second audio signals, the second audio signal being a processed version of the first audio signal, determine a parameter of an amplitude distribution for that audio signal; and

detect a degree of said processing of the first signal comprising nonlinear amplitude processing, said detection comprising comparing the determined parameters for the first and second signals; and

apply more or less aggressive echo cancellation based on the detected degree.

20. A computer device according to claim 19, wherein one or more processors are further configured to determine histograms for values corresponding to respective signal amplitudes of the first audio signal and the second audio signal respectively, said parameters being respective parameters of those histograms.