VERY LOW BIT RATE VOICE MESSAGING SYSTEM USING VARIABLE RATE BACKWARD SEARCH INTERPOLATION PROCESSING

摘要

A method and apparatus are provided for a low bit rate speech transmission. Speech spectral parameter vectors are generated from a voice message and stored in a sequence of speech spectral parameter vectors within a speech spectral parameter matrix (602). A first index identifying a first speech parameter template (614) corresponding to a first speech spectral parameter vector (604) of the sequence of speech spectral parameter vectors is transmitted. A subsequent speech spectral parameter vector (608) of the sequence is selected and a subsequent speech parameter template (618) is determined having a subsequent index. One or more intervening interpolated speech parameter templates (620) are interpolated between the first speech parameter template (614) and the subsequent speech parameter template (618). The one or more intervening speech spectral parameter vectors (606) are compared to the corresponding one or more intervening interpolated speech parameter templates (620) to derive a distance. The subsequent index is transmitted when the distance derived is less than or equal to a predetermined distance.