Patent ID: 7072835
Filing Date: 2006-07-04
Classification: G10L

Abstract:
1. A method for speech recognition comprising: a feature-amount extracting step for extracting a feature amount based on a processing frame of an input utterance; a storing step for determining whether a current processing frame is within or at the end of at least one candidate word within a hypothesis, the at least one candidate word developed from the hypothesis, and storing one or more candidate words on the basis of a first hypothesis-storage determining criterion when within the word and on the basis of a second hypothesis-storage determining criterion when at the word end; a developing step for developing the hypothesis, each candidate word within the hypothesis selected from words previously registered, by extending utterance segments to at least one processing frame following the current processing frame to express the candidate word when the candidate word is within the word and by joining a new candidate word to follow according to an inter-word connection rule when at the word end; an operating step of computing a similarity measure between the feature amount extracted from the input utterance and a frame-based feature amount of an acoustic model of the developed hypothesis for the current processing frame, and calculating a new recognition score from a) the similarity measure and b) a recognition score of the developed hypothesis of up to a frame immediately preceding the current processing frame calculated from the similarity measure; and a step of repeating the storing step, the developing step and the operating step until a last processing frame of the input utterance, and outputting the stored one or more candidate words for each processing frame as a recognition result approximate to the input utterance, in a decreasing order of recognition score, wherein the first hypothesis-storage determining criterion selects candidate words from the developed hypothesis within a predetermined threshold from a maximum value of the recognition score, wherein a number of candidate words stored according to the first hypothesis-storage determining criterion when within the word is independent of the second hypothesis-storage determining criterion, and the second hypothesis-storage determining criterion selects a subset of candidate words from among the candidate words selected according to the first hypothesis-storage determining criterion, the subset of candidate words selected according to a predetermined number of upper ranking recognition scores.