【作者】 张海；

【导师】 鲍长春；

【作者基本信息】 北京工业大学 ， 电路与系统， 2001， 硕士

【摘要】 目前，拥有长途话音质量的4kbps及4kbps以下速率的语音编码器是人们研究的热点，它们在可视电话、移动通信及个人通信等方面将有非常广阔的应用前景。本文基于波形内插（WI）编码方案开发一个3.75kbps的语音编码器，并用C语言在计算机上模拟实现。 WI编码器将语音信号表示为渐变的特征波形（CW），并将其分解为慢渐变波形（SEW）与快渐变波形（REW），以分别进行量化。其中，SEW表示语音信号中的准周期成分，REW表示语音信号中的非周期成分。 非正式主观质量测试的结果表明，未经参数量化的WI编码器的语音质量要比8kbpsG.729标准好。而量化以后，3.75kbps WI编码器的语音质量接近于G.723.1的5.3kbps标准。更多还原

【Abstract】 Recently~ there is the great interest in developing toll-quality speech coders at rates of 4kbps and below, and which are expected to be widely exploited in applications such as visual telephone~ mobile and personal communications. In this paper, a speech coder at 3.75kbps is developed based on the waveform interpolation scheme (WI), and has been simulated in floatingpoint C language.In the WI coder, the speech signal is represented by an evolving characteristic waveform (CW) . The CW is decomposed into a slowly evolving waveform and a rapidly evolving waveform, representing the quasi-periodic and non-periodic components of speech respectively,which are quantized separately.Informal subjective listening tests indicated that the unquantized WI coder is comparative with the 8kbps G.729 standard under clean input speech conditions. After quantized, the speech quality of WI coder at 3.75kbps is closed to that of G.723.l at 5.3kbps.更多还原