Speech recognition system utilizing both a long-term strategic and a short-term strategic scoring operation in a transition network thereof

Claim 1

A speech recognition system comprising: means for acoustically analyzing an input speech signal for obtaining feature parameters of the input speech signal; means for extracting a plurality of candidate phonetic segments from the feature parameters of the input speech signal, the candidate phonetic segments including acoustic feature labels of a silence, buzz, unvoiced sound and power dips; means for causing the candidate phonetic segments to be passed through transition networks constructed for respective words to be recognized to effect a word verification operation to obtain candidate words; means for determining a work score Q(k) of the candidate word by using a following equation including a first score represented by a first term and a second score represented by a second term of the following equation: ##EQU7## where μ denotes a weighing coefficient (0≦μ≦1), Sl denotes a similarity of a phonetic segment in a frame, L denotes a number of phonetic segments, S1l is a similarity of a first-order phonetic segment in a frame in which the phonetic segment takes a maximum value, and Smaxl denotes a maximum similarity of a corresponding phonetic segment; mean for selecting that candidate word having the largest candidate score Q(k) to be a result of speech recognition; and outputting the selected candidate word as said result of speech recognition.