Detecting and reducing feedback

• US 10,540,983 B2
• Filed: 06/01/2017
• Issued: 01/21/2020
• Est. Priority Date: 06/01/2017
• Status: Active Grant

• Current Assignee: Sorenson Ip Holdings, LLC
• Original Assignee: Sorenson Ip Holdings, LLC
• Inventors: Bullough, Jeffrey
• Primary Examiner(s): Jackson, Jakieda R
• Application Number:
  US15/611,441
• Publication Number:
  US 20180350378A1
• Time in Patent Office: 964 Days
• Field of Search: 381 83, 381 95, 381 96, 704226
• CPC Class Codes: G10L 15/02 Feature extraction for speech recognition; Selection of recognition unit
• CPC Class Codes: G10L 2015/025 Phonemes, fenemes or fenones being the recognition units
• 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 21/0364 for improving intelligibility
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band
• CPC Class Codes: G10L 25/51 for comparison or discrimination
• CPC Class Codes: H04M 1/76 Compensating for differences in line impedance
• CPC Class Codes: H04M 3/002 Applications of echo suppressors or cancellers in telephonic connections in two-way loud-speaking telephone systems H04M9/08, echo suppressors or cancellers per se H04B3/20
• CPC Class Codes: H04M 3/42391 where the subscribers are hearing-impaired persons, e.g. telephone devices for the deaf
• CPC Class Codes: H04R 2430/03 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 3/02 for preventing acoustic reaction , i.e. acoustic oscillatory feedback specially adapted for hearing aids H04R25/453

Abstract

A computer-implemented method to detect and reduce feedback in an audio signal is disclosed. The method may include obtaining an audio signal. The method may further include separating the audio signal into a plurality of frequency bands. The method may also include, for each frequency band of the plurality of frequency bands, determining whether the frequency band includes feedback. The method may further include, for each frequency band determined to include feedback, attenuating the frequency band. The method may also include combining each frequency band of the plurality of frequency bands to produce an output audio signal.

Claims

1. A computer-implemented method to detect and reduce feedback in a signal, the method comprising:

obtaining an audio signal;

separating the audio signal into a plurality of frequency bands;

selecting a first frequency band of the plurality of frequency bands;

obtaining a magnitude threshold and a duration threshold;

in response to the first frequency band having a magnitude greater than the magnitude threshold for a duration longer than the duration threshold, attenuating the first frequency band an amount of the attenuation determined based on a difference between the magnitude of the first frequency band and the magnitude threshold; and

combining the plurality of frequency bands, including the attenuated first frequency band, to produce an output audio signal.

2. The method of claim 1, wherein attenuating the first frequency band comprises attenuating the first frequency band from a first point in time to a second point in time, the first frequency band having a magnitude greater than the magnitude threshold for a duration longer than the duration threshold between the first point in time and the second point in time, and not attenuating the first frequency band from a third point in time to a fourth point in time, the first frequency band not having a magnitude greater than the magnitude threshold for a duration longer than the duration threshold between the third point in time and the fourth point in time.

3. The method of claim 1, wherein each of the plurality of frequency bands includes an approximately equal bandwidth of frequency.

4. The method of claim 1, wherein the magnitude threshold and the duration threshold are determined based on phonemes analysis of human speech.

5. At least one non-transitory computer readable media configured to store one or more instructions that when executed by at least one system performs the method of claim 1.

6. The method of claim 1, further comprising:

selecting a second frequency band of the plurality of frequency bands;

obtaining a second magnitude threshold and a second duration threshold, both the second magnitude threshold and the second duration threshold based on the second frequency band, the second magnitude threshold being different than the magnitude threshold and the second duration threshold being different than the duration threshold; and

in response to the second frequency band having a magnitude greater than the second magnitude threshold for a duration longer than the second duration threshold, attenuating the second frequency band,

wherein the output audio signal includes the attenuated first frequency band and the attenuated second frequency band.

7. The method of claim 6, wherein the magnitude threshold and the duration threshold are determined based on phonemes analysis of human speech in the first frequency band and the second magnitude threshold and the second duration threshold are determined based on phonemes analysis of human speech in the second frequency band.

8. The method of claim 1, further comprising:

selecting a second frequency band of the plurality of frequency bands;

obtaining a second magnitude threshold based on the second frequency band, the second magnitude threshold being different than the magnitude threshold; and

in response to the second frequency band having a magnitude greater than the second magnitude threshold for a duration longer than the duration threshold, attenuating the second frequency band,

wherein the output audio signal includes the attenuated first frequency band and the attenuated second frequency band.

9. The method of claim 1, further comprising:

selecting a second frequency band of the plurality of frequency bands;

obtaining a second duration threshold based on the second frequency band, the second duration threshold being different than the duration threshold; and

in response to the second frequency band having a magnitude greater than the magnitude threshold for a duration longer than the second duration threshold, attenuating the second frequency band,

wherein the output audio signal includes the attenuated first frequency band and the attenuated second frequency band.

10. A computer-implemented method to detect and reduce feedback in a signal, the method comprising:

obtaining an audio signal;

separating the audio signal into a plurality of frequency hands;

for each frequency band of the plurality of frequency bands, determining whether the frequency band includes feedback in response to determining that a magnitude of the frequency band is increasing over a time period equal to a duration threshold;

for each frequency band determined to include feedback, attenuating the frequency band; and

combining each frequency band of the plurality of frequency bands to produce an output audio signal.

11. The method of claim 10, wherein for each frequency band of the plurality of frequency bands, determining whether the frequency band includes feedback is further in response to determining that the magnitude of the frequency band is above a magnitude threshold over a first duration threshold.

12. The method of claim 11, wherein the magnitude threshold and the first duration threshold are determined based on phonemes analysis of human speech.

13. The method of claim 10, wherein each of the plurality of frequency bands includes an approximately equal bandwidth of frequency.

14. The method of claim 10, wherein one or more of the plurality of frequency bands include different bandwidths of frequency.

15. The method of claim 10, wherein attenuating the frequency band comprises attenuating the frequency band by one of the following:

a fixed percentage amount, an amount based on an amount of feedback in the frequency band, and the amount of feedback determined based on the magnitude of the frequency band and a first magnitude threshold.

16. At least one non-transitory computer readable media configured to store one or more instructions that when executed by at least one system performs the method of claim 10.

17. A system to detect and reduce feedback in a signal, the system comprising:

one or more processors, the one or more processors configured to;

obtain an audio signal;

separate the audio signal into a plurality of frequency bands;

select a first frequency band of the plurality of frequency bands;

obtain a magnitude threshold and a duration threshold;

in response to the first frequency band having a magnitude greater than the magnitude threshold for a duration longer than the duration threshold, attenuate the first frequency band, an amount of the attenuation determined based on a difference between the magnitude of the first frequency band and the magnitude threshold; and

combine the plurality of frequency bands, including the attenuated first frequency band, to produce an output audio signal.

18. The system of claim 17, wherein the magnitude threshold and the duration threshold are determined based on phonemes analysis of human speech.

19. The system of claim 17, wherein the first frequency band is attenuated in response to the first frequency band having a magnitude greater than the magnitude threshold for a duration longer than the duration threshold and determining that the magnitude of the first frequency band is increasing over a time period equal to a second duration threshold.

20. The system of claim 17, wherein each of the plurality of frequency bands includes an approximately equal bandwidth of frequency.