Based on the speech produce model , we find the reason of periodicity disappearance and the extremum number increase by analysing the character of speech signal when the glottal closes 于是从语音产生模型入手，详细的分析了声门闭合时刻语音信号的性质，找到了浊音信号经过小波变换后周期性消失、极值点个数增多的原因。
2.
If the wavelet transform is directly implemented in pitch detection , comparing the glottal closure singularity of speech signal with image grey break , we will not obtain the anticipative result 将声门闭合在语音信号中表现出相应的奇异性，与图像边缘的灰阶突变进行等价对比，直接将小波变换用于声门闭合奇异型的检测，并不会得到预期效果。
3.
But it is not the same with surd or the alternation of sonant and surd . on the base of the acoustics , a whole linear time - varying discrete speech produce model is established through anatomising the factors including track , driving source and lip eradiation the mechanism of speech in this paper , and we draw a conclusion that the time between glottal closure is pitch period 本文从声学理论出发，剖析了语音产生的机理，综合考虑声道、激励源和嘴唇辐射三方面的因素，建立了一个完整的、线性的和时变的语音产生的离散系统模型，得出两次声门闭合事件之间的时间间隔就是基音周期的结论。
