A high sensitive speech detector based on sign bit sequence manipulations
Yohtaro Yatsuzuka · Electronics and Communications in Japan (Part I Communications) · 1980
Abstract In a speech signal transmission by means of the pause of speech such as the DSI, the speech detection capability is significant and accurate detection of it is indispensable. This paper proposes a detector for operations in each block with improved detection characteristic realizing a shortened hangover time and a high sensitivity. These results are obtained based on the sign bit sequence matrix processing in terms of the short‐time energy, the zero crossing rate and the sign bit sequence of the input signal. Especially in processing the sign bit sequence matrix, a degree of the speech spectrum concentration is investigated by processing the sign bit sequence of the original signal as well as the obtained signal through the pre‐emphasis filter, and the sign bit sequence matrix composed of the sign bit sequence of the fundamental frequency and its harmonic sine and cosine waves. A computer simulation has indicated that a speech level of above ‐51 dB m is detected effectively without any degradation of speech quality. The average activity of speech in an international long‐distance line is reduced remarkably to 36% compared with the conventional one of 40%, and the average talkspurt is shortened to 436 ms which is half that of the conventional ones. Furthermore, it is shown that the detector has an excellent discrimination characteristic for thermal noise.