Modulation of speech signals

Patent metadata

Field	Value
Publication number	US-9240193-B2
Application number	US-201313746305-A
Country	US
Kind code	B2
Filing date	Jan 21, 2013
Priority date	Jan 21, 2013
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

Methods, systems, and devices for processing an audio signal are provided. An example method includes mapping a fundamental frequency of an audio signal to a modulation frequency. An output of the mapping is less than the fundamental frequency when the fundamental frequency is greater than an intersection frequency. The intersection frequency is a frequency at which the output of the mapping is the fundamental frequency.

First claim

What is claimed is:

1. A sound processor configured to:
receive an audio signal that includes voiced speech;
based on the audio signal, (i) generate a spectral signal, (ii) determine a modulation frequency such that the modulation frequency is within a range of pitch frequencies a recipient is capable of perceiving, wherein a ratio of the modulation frequency to a fundamental frequency of the voiced speech is less than one over the range of pitch frequencies, and (iii) modulate at the modulation frequency one or more spectral components of the spectral signal to generate a modulated spectral signal; and
send the modulated spectral signal to an output device, thereby causing the output device to deliver an output that is configured to allow the recipient to perceive at least a portion of the audio signal.

2. The sound processor of claim 1 , wherein, to determine the modulation frequency, the sound processor is configured to:
map the fundamental frequency of a portion of the audio signal to the modulation frequency, wherein the fundamental frequency is greater than an intersection frequency, and wherein the intersection frequency is a frequency at which the output of the mapping is the fundamental frequency.

3. The sound processor of claim 1 , wherein the range of pitch frequencies is between about 100 Hz to about 500 Hz.

4. The sound processor of claim 3 , wherein the range of pitch frequencies is between about 100 Hz to about 185 Hz.

5. A method of processing an audio signal, the method comprising:
detecting a plurality of amplitude peaks of M spectral components of the audio signal, wherein each of the M spectral components corresponds to one of M frequencies, and wherein M is an integer greater than one; and
for each of the M spectral components:
determining whether N amplitude peaks of the spectral component have been detected, wherein N is an integer greater than one;
beginning a period upon determining that N amplitude peaks have been detected; and
during the period, (i) including the spectral component in a first spectral signal and including the spectral component in a second spectral signal, wherein the first spectral signal is generated at a first time and the second spectral signal is generated at a second time, wherein the first time occurs before the second time; and (ii) generating and delivering to a recipient a stimulus based on each of the first spectral signal and the second spectral signal.

6. The method of claim 5 , wherein a time at which the first spectral signal is generated is approximately synchronized to detecting the N th amplitude peak.

7. The method of claim 5 , further comprising ending the period after detecting the N th +1 amplitude peak.

8. The method of claim 5 , wherein including the spectral component in the first spectral signal occurs after an interval of time of detecting the N th amplitude peak.

9. The method of claim 5 , wherein the spectral component included in the second spectral signal is substantially the same as the spectral component included in the first spectral signal.

10. The method of claim 5 , wherein a value of N depends on a range of pitch frequencies a recipient can perceive.

11. The method of claim 10 , wherein the range of pitch frequencies is between about 100 Hz to about 500 Hz.

12. The method of claim 11 , wherein the range of pitch frequencies is between about 100 Hz to about 185 Hz.

13. The method of claim 5 , further comprising:
generating at least a first stimulus based on the first spectral signal at a first time and a second stimulus based on the second spectral signal at a second time, wherein the first time precedes the second time.

14. The method of claim 13 , wherein a difference between the first time and the second time is approximately constant for two or more periods.

15. The method of claim 13 , further comprising:
determining an average of differences in times at which successive amplitude peaks included in the plurality of amplitude peaks are detected, wherein a difference between the first time and the second time depends on the average of differences.

16. The method of claim 5 , wherein determining that N amplitude peaks have been detected includes:
determining a difference between two successive amplitude peaks;
determining whether the difference is greater than a threshold difference;
in response to determining that the difference is greater than the threshold difference, zeroing a counter; and
in response to determining that the difference is less than or equal to the threshold difference, incrementing the value of the counter by one, wherein N amplitude peaks have been detected when the value of the counter equals N.

17. The method of claim 5 , wherein the period is a gate-on period.

18. A non-transitory computer-readable memory having stored therein instructions executable by a computing device to cause the computing device to perform functions for processing an audio signal comprising:
receiving an audio signal that includes voiced speech;
generating one or more spectral signals that include one or more spectral components of the audio signal; and
modulating the one or more spectral signals at a modulation rate to provide one or more modulated spectral signals, wherein a ratio of the modulation rate to a fundamental frequency of the voiced speech is less than one over a range of pitch frequencies a recipient can perceive.

19. The non-transitory computer-readable memory of claim 18 , wherein the functions further comprise:
generating one or more modulated stimulation signals based on the one or more modulated spectral signals.

20. The non-transitory computer-readable memory of claim 19 , wherein modulating the one or more spectral signals includes:
estimating the fundamental frequency of the voiced speech included in the audio signal;
determining an output of a mapping function that represents the modulation rate as a function of the fundamental frequency, wherein the mapping function depends on at least the range of pitch frequencies the recipient can perceive.

21. The non-transitory computer-readable memory of claim 19 , wherein modulating the one or more spectral signals includes adjusting a rate at which the one or more modulated stimulation signals are generated by:
detecting a plurality of amplitude peaks of the audio signal at one or more frequencies; and
generating at least one stimulation signal during one or more periods, wherein each period begins upon detecting an N th amplitude peak and ends upon detecting an N+1 th amplitude peak, and wherein N is an integer greater than one.

22. The non-transitory computer-readable memory of claim 21 , wherein a value of N depends on a ratio of fundamental frequencies of speech to pitch frequencies a recipient is capable of perceiving.

23. The non-transitory computer-readable memory of claim 20 , wherein the functions further comprise:
determining one or more statistics of the fundamental frequency over a period of time, wherein the one or more statistics include one or more of an average fundamental frequency, a maximum fundamental frequency, a minimum fundamental frequency, or a median fundamental frequency; and
modifying the mapping function based on the one or more statistics to increase a likelihood that the fundamental frequency is within an operating range, wherein the operating range depends on the range of frequencies of human speech.

24. The non-transitory co

Assignees

• Cochlear Ltd

Inventors

• James Christopher

Classifications

• G10L25/90

  Pitch determination of speech signals · CPC title

• H04R25/353 Primary

  Frequency, e.g. frequency shift or compression · CPC title

• G10L21/00 Primary

  Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility (G10L19/00 takes precedence) · CPC title

• H04R2225/31

  Aspects of the use of accumulators in hearing aids, e.g. rechargeable batteries or fuel cells · CPC title

• H04R25/70

  Adaptation of deaf aid to hearing loss, e.g. initial electronic fitting · CPC title