Speech recognition method and apparatus adapted to a plurality of

Abstract

Speech recognition in prior art uses one extracted characteristic component (x.sub.i) to represent one phoneme (X.sub.i) as spoken by one speaker. This invention provides for recognizing the same phoneme as spoken by different speakers, by deriving a group of such components (x.sub.ik), each a slight variant of the others, to allow finding one component most similar to both the specific phoneme and specific speaker, the method comprising the steps of: normalizing the sound pressure level of an input speech from an unknown speaker; analyzing the normalized voice in a plurality of channels having different frequencies; setting, with respect to the output F.sub.j of each frequency band thus analyzed, a weight .alpha..sub.j of the output F.sub.j so that weight .alpha..sub.j corresponds to a characteristic of a predetermined phoneme X.sub.i ; extracting the characteristic component x.sub.i of the phoneme X.sub.i, setting a weight .beta..sub.j of output F.sub.j so that, when the extracted characteristic component x.sub.i causes a malfunction or error due to another phoneme X.sub.e, a characteristic of phoneme X.sub.e is corresponded to; simultaneously extracting the characteristic component x.sub.e of phoneme X.sub.e and, when the difference between the characteristic components thus extracted is greater than a predetermined threshold value .gamma..sub.i, applying the difference as a characteristic parameter for the phoneme x.sub.i ; expanding the characteristic parameter to obtain a characteristic parameter group based on the characteristic parameter, each being slightly different from each other so as to be adapted for individual characteristics of different speakers; subsequently extracting from the characteristic parameter group a characteristic parameter, having maximum similarity to a reference parameter previously memorized, as an adaptive parameter adaptive to the unknown speaker; and, matching a standard pattern derived from the extracted adaptive parameters with an unknown pattern corresponding to the unknown speakers, thereby effecting recognition or analysis of the voice.