Speech spurt detecting apparatus and method with threshold adapted by

Abstract

A speech spurt detecting apparatus for detecting speech spurts in a voice signal has a storage for storing an input voice signal. A decision portion determines speech spurt sections and mute sections using a threshold value and sets one of the mute sections at a latter part of a hangover time. A mute level statistical processor estimates the noise distribution of a signal in the mute sections. A speech spurt detecting threshold value decision portion receives the average and the variance of the noise distribution from the mute level statistical processor and approximates the noise distribution to a gamma distribution to decide a speech spurt detecting threshold. A speech spurt transmitting portion outputs the voice signal in the speech spurt sections from the storage. A speech spurt level statistical processor carries out statistical processing of the speech spurt sections. The speech spurt detecting threshold value decision portion detects an error of the speech spurt detecting threshold value using the speech spurt level statistical processor and the mute level statistical processor and resets the speech spurt detecting threshold value to its initial value if the error exceeds a predetermined value. The speech spurt detecting threshold value decision portion increases the speech spurt detecting threshold value at a fixed rate in each of the speech spurt sections, and computes (the average).sup.2 /(the variance) to obtain an adjusting coefficient and computes (the adjusting coefficient).times.(the average) to obtain the speech spurt detecting threshold value.