Speech spurt detecting apparatus and method with threshold adapted by noise and speech statistics

A speech spurt detecting apparatus for detecting speech spurts in a voice signal, said speech spurt detecting apparatus comprising:

• a storage for storing an input voice signal;
• a decision portion for making a decision of speech spurt sections and mute sections from the input voice signal using a threshold value;
• a mute level statistical processor for estimating noise distribution of a signal in the mute sections by statistically processing the mute sections decided by the decision portion;
• a speech spurt detecting threshold value decision portion for deciding a speech spurt detecting threshold value considering the noise distribution such that the threshold value is unaffected by noise, wherein said speech spurt detecting threshold value decision portion increases at a fixed rate the speech spurt detecting threshold value in each of the speech spurt sections;
• and
• a speech spurt transfer portion for outputting from the storage the voice signal in the speech spurt sections.

A speech spurt detecting apparatus for detecting speech spurts in a voice signal, said speech spurt detecting apparatus comprising:

• a storage for storing an input voice signal;
• a decision portion for making a decision of speech spurt sections and mute sections from the input voice signal using a threshold value, wherein said decision portion decides a portion with its level lower than the threshold value as one of said mute sections, and sets one of the mute sections at a latter part of a hangover time;
• a mute level statistical processor for estimating noise distribution of a signal in the mute sections by statistically processing the mute sections decided by the decision portion;
• a speech spurt detecting threshold value decision portion for deciding a speech spurt detecting threshold value considering the noise distribution such that the threshold value is unaffected by noise;
• a speech spurt transfer portion for outputting from the storage the voice signal in the speech spurt sections;
• and
• a speech spurt level statistical processor for carrying out statistical processing of the speech spurt sections, wherein said speech spurt detecting threshold value decision portion detects an error of the speech spurt detecting threshold value using said speech spurt level statistical processor and said mute level statistical processor, and resets the speech spurt detecting threshold value to its initial value if the error exceeds a predetermined value.

A speech spurt detecting method for detecting speech spurts in a voice signal, said speech spurt detecting method comprising the steps of:

• storing an input voice signal;
• making a decision of speech spurt sections and mute sections from the input voice signal using a threshold value;
• estimating noise distribution of a signal in the mute sections by statistically processing the mute sections;
• deciding a speech spurt detecting threshold value considering the noise distribution such that the possibility of erroneously detecting noise as a speech signal is lowered;
• obtaining an average and a variance of the noise distribution from said mute level statistical processor and approximating the noise distribution to a gamma distribution in accordance with said average and said variance to decide a speech spurt detecting threshold value in such a way that the possibility of erroneously detecting noise as a speech signal is lowered;
• and
• outputting the voice signal in the speech spurt sections from the stored voice signal.