Techniques for howling detection

Patent metadata

Field	Value
Publication number	US-11638094-B2
Application number	US-201917057516-A
Country	US
Kind code	B2
Filing date	May 29, 2019
Priority date	Jun 11, 2018
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

A howling detector is described that is configured to receive an input signal and to determine measure of the linearity of a logarithmic representation of the energy of the input signal. In some examples, this triggers gain adjustment (e.g. of a noise control unit) and, in some further examples, the amount of the gain adjustment may be based on an estimation of the maximum stable gain of a noise control unit.

First claim

The invention claimed is:

1. A howling detector configured to:
receive an input audio signal;
determine a parameter of a portion of the input audio signal;
determine a measure of linearity of the parameter; and
compare the measure of linearity to a predetermined threshold to determine whether howling is likely or imminent on the basis of a parameter of a portion of an input signal.

2. The howling detector of claim 1 wherein the howling detector is configured to measure the parameter of the portion of the input signal.

3. The howling detector of claim 1 wherein the howling detector is configured to determine whether howling is likely or imminent on the basis of the linearity of the parameter of the portion of the input signal.

4. The howling detector of claim 3 wherein the howling detector is configured to determine the linearity of the parameter of the portion of the input signal.

5. The howling detector of claim 1 wherein the parameter is proportional to the energy of the portion of the input signal.

6. The howling detector of claim 5 wherein the parameter is proportional to the logarithm of the energy of the portion of the input signal.

7. The howling detector of claim 6 wherein the parameter of the portion of the input signal is proportional to the difference between the logarithm of the energy of the portion of the input signal and a trend line, wherein the trend line comprises a straight line representation of the logarithm of the energy of the portion of the input signal.

8. The howling detector of claim 7 wherein the parameter of the portion of the input signal is proportional to the residuals of the trend line.

9. The howling detector of claim 7 wherein the parameter of the portion of the input signal is proportional to a goodness of fit measure of the trend line over P samples.

10. The howling detector of claim 9 wherein the goodness of fit measure, r(n), is represented by:

r
⁡
(
n
)

=

∑

i
=
0

P
-
1

(

y
⁡
(

n
-
i

)

-

(

β
^

0

(
n
)

+

(

P
-
i

)

·

β
^

1

(
n
)

)

)

2

,

where y(n) is the log energy of the input signal, {circumflex over (β)} 0 (n) is the bias of the trend line and {circumflex over (β)} 1 (n) is the slope of the trend line.

11. The howling detector of claim 7 wherein the parameter is proportional to the slope of the trend line.

12. The howling detector of claim 5 wherein the parameter is proportional to a derivative of the energy of the portion of the input signal.

13. The howling detector of claim 6 wherein the parameter is proportional to a derivative of the logarithm of the energy of the portion of the input signal.

14. A gain adjuster configured to adjust the gain of a noise control circuit based on a command issued by a howling detector indicating that a measure of linearity of a parameter of a portion of an input audio signal exceeds or falls below a predetermined threshold which indicates whether howling is likely or imminent.

15. The gain adjuster of claim 14 wherein the gain adjuster is configured to adjust the gain of a noise control circuit based on the linearity of the parameter of the portion of the input signal.

16. The gain adjuster of claim 14 wherein the parameter is proportional to the energy of the portion of the input signal.

17. The gain adjuster of claim 14 wherein the parameter is proportional to the logarithm of the energy of the portion of the input signal.

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Peso Parada Pablo
• Saeidi Rahim
• Melanson John L

Classifications

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title

• H04R3/02 Primary

  for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} · CPC title

• G10K2210/108

  Communication systems, e.g. where useful sound is kept and noise is cancelled · CPC title

• G10K2210/503

  Diagnostics; Stability; Alarms; Failsafe · CPC title

• G10K11/17819 Primary

  between the output signals and the reference signals, e.g. to prevent howling · CPC title