Abstract: A speech recognition system for recognizing a system user's speech can shorten a recognition period by reducing the amount of necessary calculations without deteriorating the accuracy rate of recognition. The speech recognition system successively calculates statistical probabilities of acoustic models, outputs a one sentence recognition result corresponding to acoustic models having the highest reliability when the one sentence is detected and stops the following calculations.

Abstract: This invention relates to a method of recognizing input speech of many unspecific people. Feature parameters representing both a short-time average spectrum envelope characteristic of the input speech, and regression coefficients obtained from the outputs from a wide-band filter bank. The regression coefficients represent the rough directionality of the characteristic of change in the spectrum of the speech signal. Distance is measured between the feature parameters and standard patterns stored in a storage means. The distance between the feature parameters and the stored pattern which is smallest of all the patterns is found to recognize said input speech.

Abstract: In a speech transmission or storage system using LPC parameters and a Baseband Signal derived from the prediction error signal, the synthesis excitation signal is formed from the baseband plus high-frequency regeneration, which is then spectrum-flattened for proper synthesis.

Abstract: In a speech analysis-synthesis system for the narrow band transmission of a speech signal, speech is separated into a plurality of spectrum information (K.sub.i), average (V.sub.0) of linear prediction error signal, pitch period (L), voiced/unvoiced decision signal (V/UV), a pseudo exciting signal (I) which is a part of a linear prediction error signal or an impulse response of the same, and a frame information which determines the interval and the duration of the spectrum analyzation, then, in a receive side, the product of said pseudo excitation signal (I) and said pitch period (L), a white noise is switched according to said voiced/unvoiced decision signal (V/UV), and the output of the switch is applied to a synthesis filter which attaches correlation components to an input signal according to spectrum information (K.sub.i) to provide synthesized speech.

Abstract: A system for detecting the pitch of a voice signal, in which a plurality of pitch searching periods are determined so that pitch components of multiple relationship are not included in each of the pitch searching periods, and in which after detecting a pitch searching period including the pitch from the pitch searching periods, the pitch searching periods are adaptively shifted in a mannger to follow the change direction of the pitch predicted from the result of detection of the detected pitch.