Key-subword spotting for speech recognition and understanding

• US 20020013706A1
• Filed: 06/06/2001
• Published: 01/31/2002
• Est. Priority Date: 06/07/2000
• Status: Abandoned Application

• Current Assignee: Sony International Europe Gmbh (Sony Group Corp.)
• Original Assignee: Sony International Europe Gmbh (Sony Group Corp.)
• Inventors: Profio, Ugo Di
• Application Number:
  US09/875,765
• Publication Number:
  US 20020013706A1
• Time in Patent Office: Days
• US Class Current: 704/254
• CPC Class Codes: G10L 15/00 Speech recognition G10L17/00 takes precedence
• CPC Class Codes: G10L 15/08 Speech classification or search
• CPC Class Codes: G10L 15/10 using distance or distortion measures between unknown speech and reference templates
• CPC Class Codes: G10L 15/18 using natural language modelling
• CPC Class Codes: G10L 15/1815 Semantic context, e.g. disambiguation of the recognition hypotheses based on word meaning
• CPC Class Codes: G10L 15/22 Procedures used during a speech recognition process, e.g. man-machine dialogue
• CPC Class Codes: G10L 15/26 Speech to text systems G10L15/08 takes precedence
• CPC Class Codes: G10L 15/28 Constructional details of speech recognition systems
• CPC Class Codes: G10L 15/32 Multiple recognisers used in sequence or in parallel; Score combination systems therefor, e.g. voting systems
• CPC Class Codes: G10L 2015/085 Methods for reducing search complexity, pruning
• CPC Class Codes: G10L 2015/088 Word spotting
• CPC Class Codes: G10L 2015/228 of application context

Abstract

In spontaneous speech, utterances are often ungrammatical and/or poorly modeled by conventional grammars, keyword spotting for detection of relevant words sequences could be ineffective and the recognition task cannot be improved. Therefore, a key-subword spotting strategy is proposed to catch in-word semantics on basis of a first stage recognition of an unknown word and thus both the speech recognition and the understanding tasks are facilitated by a second stage recognition of the same unknown word on basis of a vocabulary reduced according to the spotted key-subword.

Claims

1. Method to recognize speech phrases, characterized by the following steps:

performing key-subphrase spotting to determine a category of a received speech phrase; and

in case a category is determined

performing a second stage recognition on the received speech phrase by using a restricted vocabulary corresponding to the determined category to generate a second recognition result.

2. Method according to claim 1, characterized by

performing a first stage recognition on the received speech phrase by using a general vocabulary to generate a first recognition result, wherein the key-subphrase spotting is performed on the basis of the first recognition result.

3. Method according to claim 2, characterized in that the first recognition result is output as recognition result in case no category is determined, and the second recognition result is output as recognition result in case a category is determined.

4. Method according to anyone of claims 1 to 3, characterized in that a set of more than one key-subphrase might be found during the key-subphrase spotting to determine the category of the speech phrase.

5. Method according to anyone of the preceding claims, characterized in that a category is a set of speech phrases each comprising a set of at least one key-subphrase.

6. Method according to anyone of the preceding claims, characterized in that a category is a set of speech phrases each related to a set of at least one key-subphrase.

7. Method according to anyone of the preceding claims, characterized in that a speech phrase is a word and a key-subphrase is a part of a word which is recognizable.

8. Method according to anyone of the preceding claims, characterized in that the vocabulary and/or a language model used in the first stage recognition and/or the second stage recognition is restricted according to additional/external knowledge about the speech phrase to be recognized.

9. Speech recognizer, characterized by

a key-subphrase detector (2) for performing key-subphrase spotting to determine a category of a received speech phrase;

and

a second stage recognition unit (5) for performing a second stage recogition on the received speech phrase by using a restricted vocabulary corresponding to the determined category and to generate a second recognition result in case a category is determined by the key-subphrase detector (2).

10. Speech recognizer according to claim 9, characterized by a first stage recognition unit (1) for performing a first stage recognition on the received speech phrase by using a general vocabulary and to generate a first recognition result on basis of which the key-subphrase spotting is performed.

11. Speech recognizer according to claim 9 or 10, characterized in that the first stage recognition unit (1), the key-subphrase detector (2), and/or the second stage recognition unit (6) perform a respective low-level speech recognition independently based on at least one recognition engine (3).

12. Speech recognizer according to claim 9, 10 or 11, characterized by a vocabulary selector (8) which selects certain entries of the general vocabulary (7) on basis of predefined rules according to key-subphrases input thereto to generate the restricted vocabulary (7).