关键词: 静音检测，小波，支持向量机，短时自适应权重

Abstract: The proposed VAD uses MFCC of multiresolution spectrum and two classical audio parameters as audio feature,and prejudges silence by detection of multi gate zero cross ratio, and classifies noise and voice by Support Vector Machines. New speech mixing algorithm used in Multipoint Control Unit(MCU) of conferences imposed short time power of each audio stream as mixing weight vector, and was designed for parallel processing in program. Various experiments show,proposed VAD algorithm achieves overall better performance in all SNRs than VAD of G. 729b and other VAD, output audio of new speech mixing algorithm has excellent hearing perceptibility, and its computational time delay is small enough to satisfy the needs of real-time transmission, and MCU computation is lower than that based on G. 729b VAD.

Key words: Voice activity detection, Wavelet, SVM, Short time adaptive weighted