Abstract: Identification information of a speech spurt, hangover and pause is used to indicate that a digital voice signal is the speech spurt, hangover or pause. While the identification information of a speech spurt, hangover and pause is indicative of the speech spurt, a voice level adjuster does not attenuate the digital voice signal, and the voice signal/third signal combiner mixes it with a third signal which undergoes the maximum attenuation through a third signal level adjuster. While the identification information of a speech spurt, hangover and pause is indicative of the hangover, the voice level adjuster gradually attenuates the digital voice signal. This is because the level of the voice signal is expected to be high in the first half of the hangover period, but to decay in its latter half to such a level that it is dispensable for speech recognition.

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.