Frame erasure concealment technique for a bitstream-based feature extractor

• US 8,359,199 B2
• Filed: 11/29/2011
• Issued: 01/22/2013
• Est. Priority Date: 12/10/1999
• Status: Expired due to Fees

• Current Assignee: Cerence Inc., Cerence Operating Company (Cerence Inc.)
• Original Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Inventors: Cox, Richard Vandervoort, Kim, Hong Kook
• Primary Examiner(s): Opsasnick, Michael N
• Application Number:
  US13/306,201
• Publication Number:
  US 20120072214A1
• Time in Patent Office: 420 Days
• Field of Search: 704/236
• US Class Current: 704/236
• CPC Class Codes: G10L 15/02 Feature extraction for speech recognition; Selection of recognition unit
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A frame erasure concealment technique for a bitstream-based feature extractor in a speech recognition system particularly suited for use in a wireless communication system operates to “delete” each frame in which an erasure is declared. The deletions thus reduce the length of the observation sequence, but have been found to provide for sufficient speech recognition based on both single word and “string” tests of the deletion technique.

Claims

1. A method of frame erasure concealment, comprising:

detecting a frame erasure;

computing a probability of an observation sequence based on a decoding algorithm in response to detecting the frame erasure; and

deleting an observation vector of the observation sequence, the observation vector associated with the frame erasure, wherein deleting the observation vector of the observation sequence comprises;

measuring a Euclidean distance between line spectrum pairs of contiguous frames, wherein the Euclidian distance is given by

2. The method of claim 1, further comprising:

decoding the observation sequence based on a hidden Markov model process.

3. The method of claim 1, wherein computing the probability of an observation sequence based on the decoding algorithm comprises:

determining a missing observation vector; and

computing the probability of the observation sequence using a missing feature theory based on the missing observation vector.

4. The method of claim 1, wherein detecting the frame erasure comprises:

determining an error in bits most sensitive to error within a frame; and

declaring the frame erasure associated with the frame.

5. The method of claim 4, wherein the bits most sensitive to error in a frame includes line spectrum pair information bits and gain information bits.

6. A system of frame erasure concealment, comprising:

means for detecting a frame erasure;

means for computing a probability of an observation sequence based on a decoding algorithm in response to detecting a frame erasure; and

means for deleting an observation vector of the observation sequence, the observation vector associated with the frame erasure, wherein the means for deleting the observation vector of the observation sequence comprises;

means for measuring a Euclidean distance between line spectrum pairs of contiguous frames, wherein the Euclidian distance is given by

7. The system of claim 6, further comprising:

means for decoding the observation sequence based on a Markov model process.

8. The system of claim 6, wherein the means for computing a probability of an observation sequence comprises:

means for determining a missing observation vector; and

means for computing the probability of the observation sequence using a missing feature theory based on the missing observation vector.

9. The system of claim 6, wherein the means for detecting the frame erasure comprises:

means for determining an error in bits most sensitive to error within a frame; and

means for declaring the frame erasure associated with the frame.

10. The system of claim 9, wherein the bits most sensitive to error in a frame includes line spectrum pair information bits and gain information bits.