Speech dereverberation methods, devices and systems

• US 9,520,140 B2
• Filed: 03/31/2014
• Issued: 12/13/2016
• Est. Priority Date: 04/10/2013
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Goesnar, Erwin, Dickins, Glenn N., Gunawan, David
• Primary Examiner(s): Yen, Eric
• Application Number:
  US14/782,746
• Publication Number:
  US 20160035367A1
• Time in Patent Office: 988 Days
• US Class Current: 1/1
• 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 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: G10L 25/21 the extracted parameters being power information

Abstract

Improved audio data processing method and systems are provided. Some implementations involve dividing frequency domain audio data into a plurality of subbands and determining amplitude modulation signal values for each of the plurality of subbands. A band-pass filter may be applied to the amplitude modulation signal values in each subband, to produce band-pass filtered amplitude modulation signal values for each subband. The band-pass filter may have a central frequency that exceeds an average cadence of human speech. A gain may be determined for each subband based, at least in part, on a function of the amplitude modulation signal values and the band-pass filtered amplitude modulation signal values. The determined gain may be applied to each subband.

Claims

1. A method, comprising:

receiving a signal that includes frequency domain audio data;

applying a filterbank to the frequency domain audio data to produce frequency domain audio data in a plurality of subbands;

determining amplitude modulation signal values for the frequency domain audio data in each subband;

applying a band-pass filter to the amplitude modulation signal values in each subband to produce band-pass filtered amplitude modulation signal values for each subband, the band-pass filter having a central frequency that exceeds an average cadence of human speech;

determining a gain for each subband based, at least in part, on a function of the amplitude modulation signal values and the band-pass filtered amplitude modulation signal values; and

applying a determined gain to each subband.

2. The method of claim 1, wherein the process of determining amplitude modulation signal values involves determining log power values for the frequency domain audio data in each subband.

3. The method of claim 1, wherein a band-pass filter for a lower-frequency subband passes a larger frequency range than a band-pass filter for a higher-frequency subband.

4. The method of claim 1, wherein the band-pass filter for each subband has a central frequency in the range of 10-20 Hz.

5. The method of claim 4, wherein the band-pass filter for each subband has a central frequency of approximately 15 Hz.

6. The method of claim 1, wherein the function includes an expression in the form of R10^A.

7. The method of claim 6, wherein R is proportional to a band-pass filtered amplitude modulation signal value divided by an amplitude modulation signal value.

8. The method of claim 6, wherein A is proportional to an amplitude modulation signal value minus a band-pass filtered amplitude modulation signal value.

9. A non-transitory medium having software stored thereon, the software including instructions for controlling at least one apparatus to perform the method of claim 1.

10. A device, comprising:

an interface system; and

a logic system configured to

receive, via the interface system, a signal that includes frequency domain audio data;

apply a filterbank to the frequency domain audio data to produce frequency domain audio data in a plurality of subbands;

determine amplitude modulation signal values for the frequency domain audio data in each subband;

apply a band-pass filter to the amplitude modulation signal values in each subband to produce band-pass filtered amplitude modulation signal values for each subband, the band-pass filter having a central frequency that exceeds an average cadence of human speech;

determine a gain for each subband based, at least in part, on a function of the amplitude modulation signal values and the band-pass filtered amplitude modulation signal values; and

apply a determined gain to each subband.

11. The device of claim 10, wherein the process of determining amplitude modulation signal values involves determining log power values for the frequency domain audio data in each subband.

12. The device of claim 10, wherein a band-pass filter for a lower-frequency subband passes a larger frequency range than a band-pass filter for a higher-frequency subband.

13. The device of any one of claim 10, wherein the band-pass filter for each subband has a central frequency in the range of 10-20 Hz.

14. The device of claim 13, wherein the band-pass filter for each subband has a central frequency of approximately 15 Hz.

15. The device of claim 10, wherein the function includes an expression in the form of R10^A.

16. The device of claim 15, wherein R is proportional to a band-pass filtered amplitude modulation signal value divided by an amplitude modulation signal value.

17. The device of claim 15, wherein A is proportional to an amplitude modulation signal value minus a band-pass filtered amplitude modulation signal value.

18. The device of claim 15, wherein A includes a constant that indicates a rate of suppression.

19. The device of claim 15, wherein determining the gain involves determining whether to apply a gain value produced by the expression in the form of R10^A or a maximum suppression value.

20. The device of claim 10, wherein the logic system is further configured to

determine a diffusivity of an object;

and

determine the maximum suppression value for the object based, at least in part, on the diffusivity.