Speech recognition apparatus, speech recognition method, and storage medium

• US 7,013,277 B2
• Filed: 02/26/2001
• Issued: 03/14/2006
• Est. Priority Date: 02/28/2000
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Minamino, Katsuki, Lucke, Helmut, Asano, Yasuharu, Ogawa, Hiroaki
• Primary Examiner(s): Abebe, Daniel
• Application Number:
  US09/794,887
• Publication Number:
  US 20010020226A1
• Time in Patent Office: 1,842 Days
• Field of Search: 704/207, 704/211, 704/222, 704/231, 704/246, 704/251, 704/255, 704/257
• US Class Current: 704/257
• CPC Class Codes: G10L 15/193 Formal grammars, e.g. finite state automata, context free grammars or word networks
• CPC Class Codes: G10L 2015/085 Methods for reducing search complexity, pruning

Abstract

A preliminary word-selecting section selects one or more words following words which have been obtained in a word string serving as a candidate for a result of speech recognition; and a matching section calculates acoustic or linguistic scores for the selected words, and forms a word string serving as a candidate for a result of speech recognition according to the scores. A control section generates word-connection relationships between words in the word string serving as a candidate for a result of speech recognition, sends them to a word-connection-information storage section, and stores them in it. A re-evaluation section corrects the word-connection relationships stored in the word-connection-information storage section 16, and the control section determines a word string serving as the result of speech recognition according to the corrected word-connection relationships.

Claims

1. A speech recognition apparatus for recognizing an input speech as a recognized speech, comprising:

a feature extracting means for extracting feature amounts from the input speech;

a preliminary word-selecting means for selecting words on the basis of the feature amounts by referring to a first database;

a matching means for calculating acoustic and linguistic scores for the selected words and forming a word string serving as a candidate for the recognized speech by referring to a second database;

wherein the second database incorporates more precise acoustic model, phoneme information, and grammar rules than the first database;

a control means for generating word-connection-information between words in the word string;

the word-connection-information including acoustic and linguistic scores for each word in the word string;

a re-evaluation means for re-evaluating the word string and correcting the word-connection-information by referring to a third database;

wherein the third database incorporates more precise acoustic models, phoneme information, and grammar rules than the second database; and

the control means determining the recognized speech by correcting the word string on the basis of the corrected word-connection-information.

2. The speech recognition apparatus according to claim 1, wherein the word-connection-information is stored in a word-connection-information storage section as a graph structure expressed by nodes and arcs.

3. The speech recognition apparatus according to claim 1, wherein the word-connection-information includes a starting time and an ending time for each word in the word string.

4. The speech recognition apparatus according to claim 1, wherein the matching means forms the word string by connecting words from the selected words as their acoustic and linguistic scores are calculated;

and

each time a word is connected to the word string, the word string is re-evaluated and the word-connection-information is corrected.

5. The speech recognition apparatus according to claim 1, wherein the preliminary word-selecting means selects words and the matching means forms the word string by referring to the word-connection-information.

6. A speech recognition method of recognizing an input speech as a recognized speech, comprising the steps of:

a feature extracting step of extracting feature amounts from the input speech;

a preliminary word-selecting step of selecting words on the basis of the feature amounts by referring to a first database;

a matching step of calculating acoustic and linguistic scores for the selected words and forming a word string serving as a candidate for the recognized speech by referring to a second database;

wherein the second database incorporates more precise acoustic model, phoneme information, and grammar rules than the first database;

a control step of generating word-connection-information between words in the word string;

the word-connection-information including acoustic and linguistic scores for each word in the word string;

a re-evaluation step of re-evaluating the word string and correcting the word-connection-information by referring to a third database;

wherein the third database incorporates more precise acoustic models, phoneme information, and grammar rules than the second database; and

a second control step of determining the recognized speech by correcting the word string on the basis of the corrected word-connection-information.

7. A recording medium for storing a program which executes on a computer for recognizing an input speech as a recognized speech, the program comprising:

a feature extracting step of extracting feature amounts from the input speech;

a preliminary word-selecting step of selecting words on the basis of the feature amounts by referring to a first database;

a matching step of calculating acoustic and linguistic scores for the selected words and forming a word string serving as a candidate for the recognized speech by referring to a second database;

wherein the second database incorporates more precise acoustic model, phoneme information, and grammar rules than the first database;

a control step of generating word-connection-information between words in the word string;

the word-connection-information including acoustic and linguistic scores for each word in the word string;

a re-evaluation step of re-evaluating the word string and correcting the word-connection-information by referring to a third database;

wherein the third database incorporates more precise acoustic models, phoneme information, and grammar rules than the second database; and

a second control step of determining the recognized speech by correcting the word string on the basis of the corrected word-connection-information.