Patent Document ID: 4060694
Application ID: 05581083
Patent Status: 1

Claim One:
1. Speech recognition method adapted to a plurality of speakers comprising the steps of storing a plurality of reference parameters for a reference speaker where said reference parameters comprise a sentence of a predetermined vocabulary; first extracting a characteristic parameter for each phoneme from said sentence when it is uttered by said reference speaker, and storing a characteristic parameter corresponding to each said phoneme during said storing step where all of said characteristic parameters comprise said reference parameters and where each characteristic parameter x.sub.i is extracted in accordance with the following equation ##EQU9## the foregoing equation being implemented by (a) dividing each phoneme into n frequency bands where F.sub.j is the output of the j.sup.th band, (b) respectively weighting each of the outputs the bands where the weight for the j.sup.th band for x.sub.i is .alpha..sub.j and the weight for a phoneme which can erroneously be recognized as x.sub.i is .beta..sub.j, (c) establishing a predetermined threshold .gamma..sub.i and (d) subtracting the .beta..sub.j weighted F.sub.j outputs and .gamma..sub.i from the .alpha..sub.j weighted F.sub.j outputs to obtain x.sub.i ; extracting the characteristic parameters from said sentence when uttered by an unknown speaker in accordance with the following equation ##EQU10## where k = 0, 1, 2,. .. p-1, the foregoing equation being implemented by said first extracting step and p-1 further extracting steps where each of said further extracting step comprises the same steps (a) through (d) comprising said first extracting step except for respective variations in the values of .alpha..sub.j and .beta..sub.j where .alpha..sub.jk is the k.sup.th variation of .alpha..sub.j and .beta..sub.jk is the k.sup.th variation of .beta..sub.j whereby p characteristic parameters are extracted for each phoneme of said sentence; individually comparing said p characteristic parameters of each phoneme with the reference characteristic parameter extracted for said phoneme from said sentence uttered by said reference speaker; selecting for each said phoneme the one characteristic parameter from said p characteristic parameters which most closely compares with said reference characteristic parameters, in response to the selected characteristic parameter, selecting from the first extracting steps and said further extracting steps that extracting step which extracted the selected characteristic parameter for each phoneme whereby the selected extracting step is then employed for said unknown speaker; and in response to the selected extracting step, utilizing the characteristic parameters of any sentence using said vocabulary uttered by said unknown speaker to effect recognition of said last-mentioned sentence.