Method and apparatus for noise suppression within a distributed speech recognition system

• US 20040148160A1
• Filed: 01/23/2003
• Published: 07/29/2004
• Est. Priority Date: 01/23/2003
• Status: Abandoned Application

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ramabadran, Tenkasi
• Application Number:
  US10/349,840
• Publication Number:
  US 20040148160A1
• Time in Patent Office: Days
• US Class Current: 704/221
• CPC Class Codes: G10L 15/30 Distributed recognition, e.g. in client-server systems, for mobile phones or network applications
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

A method and apparatus for noise suppression within a distributed speech recognition system is provided herein. Mel-frequency cepstral coefficients (MFCCs) values are converted to filter bank outputs (F′₀ through F′₂₂). The filter bank outputs are then used by a noise suppressor (303) for channel energy estimation, noise energy estimation, etc. Noise-suppression takes place on F′₀ through F′₂₂ and the noise-suppressed filter bank outputs F″₀ through F″₂₂ are converted back to MFCC values.

Claims

1. A method for noise suppression within a distributed speech recognition system, the method comprising the steps of:

receiving a plurality of Mel-frequency cepstral coefficients (MFCCs);

converting the plurality of MFCCs into a plurality of filter bank outputs;

filtering the plurality of filter bank outputs to produce filtered filter bank outputs; and

converting the filtered filter bank outputs to a second plurality of MFCCs.

2. The method of claim 1 wherein the step of filtering the plurality of filter bank outputs comprises the step of performing noise suppression on the plurality of filter bank outputs.

3. The method of claim 1 wherein the step of receiving the plurality of MFCC components comprises the step of receiving C₀ through C₁₂.

4. The method of claim 1 further comprising the step of utilizing the second plurality of MFCCs for speech synthesis.

5. The method of claim 1 further comprising the step of utilizing the second plurality of MFCCs for speech recognition.

6. An apparatus comprising:

a receiver outputting a first plurality of Mel-frequency cepstral coefficients (MFCCs);

a first noise suppressor having the first plurality of MFCCs as an input and outputting a first plurality of filtered MFCC values; and

speech synthesis circuitry having the filtered MFCC values as an input and outputting synthesized speech based on the first plurality of filtered MFCC values.

7. The apparatus of claim 6 wherein the receiver comprises a radio frequency receiver.

8. The apparatus of claim 6 further comprising:

a second noise suppressor having the first plurality of MFCCs as an input and outputting a second plurality of filtered MFCC values; and

speech recognition circuitry having the second plurality of filtered MFCCs as an input and utilizing the second plurality of filtered MFCCs for speech recognition.

9. An apparatus comprising:

a receiver outputting a first plurality of Mel-frequency cepstral coefficients (MFCCs);

a first noise suppressor having the first plurality of MFCCs as an input and outputting a first plurality of filtered MFCC values; and

speech recognition circuitry having the first plurality of filtered MFCCs as an input and utilizing the first plurality of filtered MFCCs for speech recognition.

10. The apparatus of claim 9 wherein the receiver comprises a radio frequency receiver.

11. An apparatus comprising:

a spectral converter having a plurality of Mel-frequency cepstral coefficients (MFCCs) as an input and outputting a plurality of filter bank outputs in the spectral domain;

a noise suppressor having the filter bank outputs as an input and outputting noise-suppressed filter bank outputs; and

a DSR signal generator having the noise-suppressed filter bank outputs as an input and outputting a second plurality of MFCCs based on the noise-suppressed filter bank outputs.