Patent ID: 7627474

Claim:
A computer-implemented speech recognition method comprising: layering a central lexicon in a tree structure with respect to recognition-subject vocabularies; detecting a speech section of a user from the speech signal whose noise is suppressed, and extracting a feature vector that will be used in recognizing a speech from the detected speech section; coverting sequence of the extracted feature vector into N number of candidate phoneme sequences; performing multi-pass symbol matching between a phoneme sequence and a phonetic sequence of the central lexicon layered in the tree structure; and selecting a final speech recognition result via a Viterbi search process using a detailed acoustic model with respect to candidate vocabularies selected by the multi-pass symbol matching, wherein the tree structure comprises a certain node to assign to the node in the lexicon group tree and a terminal node to define lexicons which are separated from the central lexicon assigned to the node at an interval less than a predetermined standard as a neighborhood lexicons, and wherein the method is performed, using at least one processor.