说明：  对语音编码技术的特点进行了分析与研究, 对波形编码,声码器和混合编码三种主要 的语音编码进行了比较, 并介绍了GSM 和CD
(This paper analyzes and studies the characteristics of speech coding technology, compares the three main speech codes: waveform coding, vocoder and hybrid coding, and introduces GSM and CD.)