Speech recognition apparatus, speech recognition method, and recording medium

Abstract

In order to prevent degradation of speech recognition accuracy due to an unknown word, a dictionary database has stored therein a word dictionary in which are stored, in addition to words for the objects of speech recognition, suffixes, which are sound elements and a sound element sequence, which form the unknown word, for classifying the unknown word by the part of speech thereof. Based on such a word dictionary, a matching section connects the acoustic models of an sound model database, and calculates the score using the series of features output by a feature extraction section on the basis of the connected acoustic model. Then, the matching section selects a series of the words, which represents the speech recognition result, on the basis of the score.

What is claimed is:  
     
         1 . A speech recognition apparatus for calculating a score indicating the likelihood of a speech recognition result of input speech and for performing continuous speech recognition on said speech based on the score, said speech recognition apparatus comprising: 
 extraction means for extracting features of said speech from said speech;    calculation means for calculating said score using said features on the basis of a dictionary in which unknown-word-forming elements, which are elements forming an unknown word, for classifying an unknown word by an attribute thereof and words for the object of speech recognition are entered; and    selection means for selecting a series of said words, which represents a speech recognition result, on the basis of said score.    
     
     
         2 . A speech recognition apparatus according to    claim 1   , wherein in said dictionary, the unknown-word-forming elements for classifying an unknown word by a part of speech thereof are entered.  
     
     
         3 . A speech recognition apparatus according to    claim 2   , wherein in said dictionary, suffixes are entered as said unknown-word-forming elements.  
     
     
         4 . A speech recognition apparatus according to    claim 3   , wherein in said dictionary, phonemes which form an unknown word are entered together with said suffixes.  
     
     
         5 . A speech recognition apparatus according to    claim 1   , wherein in said dictionary, unknown-word-forming elements for classifying an unknown word by a language thereof are entered.  
     
     
         6 . A speech recognition apparatus according to    claim 1   , further comprising said dictionary.  
     
     
         7 . A speech recognition method for calculating a score indicating the likelihood of a speech recognition result of input speech and for performing continuous speech recognition on said speech based on the score, said speech recognition method comprising the steps of: 
 extracting features of said speech from said speech;    calculating said score using said features on the basis of a dictionary in which unknown-word-forming elements, which are elements forming an unknown word, for classifying an unknown word by an attribute thereof and words for the object of speech recognition are entered; and    selecting a series of said words, which represents a speech recognition result, on the basis of said score.    
     
     
         8 . A recording medium having a program recorded therein, said program comprising the steps of: 
 extracting features of said speech from said speech;    calculating said score using said features on the basis of a dictionary in which unknown-word-forming elements, which are elements forming an unknown word, for classifying an unknown word by an attribute thereof and words for the object of speech recognition are entered; and    selecting a series of said words, which represents a speech recognition result, on the basis of said score.