ADAPTIVE VOICE INTELLIGIBILITY PROCESSOR

• US 20130030800A1
• Filed: 07/26/2012
• Published: 01/31/2013
• Est. Priority Date: 07/29/2011
• Status: Active Grant

• Current Assignee: DTS, Inc. (Adeia Inc.)
• Original Assignee: DTS, Inc. (Adeia Inc.)
• Inventors: Tracey, James, He, Xing, Noh, Daekyong
• Granted Patent: US 9,117,455 B2
• Time in Patent Office: Days
• US Class Current: 704/219
• CPC Class Codes: G10L 19/07 Line spectrum pair [LSP] vocoders
• CPC Class Codes: G10L 21/003 Changing voice quality, e.g. pitch or formants
• CPC Class Codes: G10L 21/0316 by changing the amplitude
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 25/15 the extracted parameters being formant information

Abstract

Systems and methods for adaptively processing speech to improve voice intelligibility are described. These systems and methods can adaptively identify and track formant locations, thereby enabling formants to be emphasized as they change. As a result, these systems and methods can improve near-end intelligibility, even in noisy environments. The systems and methods can be implemented in Voice-over IP (VoIP) applications, telephone and/or video conference applications (including on cellular phones, smart phones, and the like), laptop and tablet communications, and the like. The systems and methods can also enhance non-voiced speech, which can include speech generated without the vocal track, such as transient speech.

Claims

1. A method of adjusting a voice intelligibility enhancement, the method comprising:

receiving an input voice signal;

obtaining a spectral representation of the input voice signal with a linear predictive coding (LPC) process, the spectral representation comprising one or more formant frequencies;

adjusting the spectral representation of the input voice signal with one or more processors to produce an enhancement filter configured to emphasize the one or more formant frequencies;

applying the enhancement filter to a representation of the input voice signal to produce a modified voice signal with enhanced formant frequencies;

detecting an envelope based on the input voice signal;

analyzing the envelope of the modified voice signal to determine one or more temporal enhancement parameters; and

applying the one or more temporal enhancement parameters to the modified voice signal to produce an output voice signal;

wherein at least said applying the one or more temporal enhancement parameters is performed by one or more processors.

2. The method of claim 1, wherein said applying the one or more temporal enhancement parameters to the modified voice signal comprises sharpening peaks in the one or more envelopes of the modified voice signal to emphasize selected consonants in the modified voice signal.

3. The method of claim 1, wherein said detecting the envelope comprises detecting an envelope of one or more of the following:

the input voice signal and the modified voice signal.

4. The method of claim 1, further comprising applying an inverse filter to the input voice signal to produce an excitation signal, such that said applying the enhancement filter to the representation of the input voice signal comprises applying the enhancement filter to the excitation signal.

5. A system for adjusting a voice intelligibility enhancement, the system comprising:

an analysis module configured to obtain a spectral representation of at least a portion of an input audio signal, the spectral representation comprising one or more formant frequencies;

a formant enhancement module configured to generate an enhancement filter configured to emphasize the one or more formant frequencies;

the enhancement filter configured to be applied to a representation of the input audio signal with one or more processors to produce a modified voice signal; and

a temporal enveloper shaper configured to apply a temporal enhancement to the modified voice signal based at least in part on one or more envelopes of the modified voice signal.

6. The system of claim 5, wherein the analysis module is further configured to obtain the spectral representation of the input audio signal using a linear predictive coding technique configured to generate coefficients that correspond to the spectral representation.

7. The system of claim 6, further comprising a mapping module configured to map the coefficients to line spectral pairs.

8. The system of claim 7, further comprising modifying the line spectral pairs to increase gain in the spectral representation corresponding to the formant frequencies.

9. The system of claim 5, wherein the enhancement filter is further configured to be applied to one or more of the following:

the input audio signal and an excitation signal derived from the input audio signal.

10. The system of claim 5, wherein the temporal envelope shaper is further configured to subdivide the modified voice signal into a plurality of bands, and wherein the one or more envelopes correspond to an envelope for at least some of the plurality of bands.

11. The system of claim 5, further comprising a voice enhancement controller configured to adjust a gain of the enhancement filter based at least partly on an amount of detected environmental noise in an input microphone signal.

12. The system of claim 11, further comprising a voice activity detector configured to detect voice in the input microphone signal and to control the voice enhancement controller responsive to the detected voice.

13. The system of claim 12, wherein the voice activity detector is further configured to cause the voice enhancement controller to adjust the gain of the enhancement filter based on a previous noise input responsive to detecting voice in the input microphone signal.

14. The system of claim 11, further comprising a microphone calibration module configured to set a gain of a microphone configured to receive the input microphone signal, wherein the microphone calibration module is further configured to set the gain based at least in part on a reference signal and a recorded noise signal.

15. A system for adjusting a voice intelligibility enhancement, the system comprising:

a linear predictive coding analysis module configured to apply a linear predictive coding (LPC) technique to obtain LPC coefficients that correspond to a spectrum of an input voice signal, the spectrum comprising one or more formant frequencies;

a mapping module configured to map the LPC coefficients to line spectral pairs; and

a formant enhancement module comprising one or more processors, the formant enhancement module configured to modify the line spectral pairs to thereby adjust the spectrum of the input voice signal and produce an enhancement filter configured to emphasize the one or more formant frequencies;

the enhancement filter configured to be applied to a representation of the input voice signal to produce a modified voice signal.

16. The system of claim 15, further comprising a voice activity detector configured to detect voice in an input microphone signal and to cause a gain of the enhancement filter to be adjusted responsive to detecting voice in the input microphone signal.

17. The system of claim 16, further comprising a microphone calibration module configured to set a gain of a microphone configured to receive the input microphone signal, wherein the microphone calibration module is further configured to set the gain based at least in part on a reference signal and a recorded noise signal.

18. The system of claim 15, wherein the enhancement filter is further configured to be applied to one or more of the following:

the input voice signal and an excitation signal derived from the input voice signal.

19. The system of claim 15, further comprising a temporal enveloper shaper configured to apply a temporal enhancement to the modified voice signal based at least in part on one or more envelopes of the modified voice signal.

20. The system of claim 19, wherein the temporal envelope shaper is further configured to sharpen peaks in the one or more envelopes of the modified voice signal to emphasize selected portions of the modified voice signal.