低速率声码器激励参数的DCT-M模型  

DCT-M model for the excitation parameter in low bit rate vocoders

作　　者：党晓妍[1] 唐昆[1] 

机构地区：[1]清华大学电子工程系微波与数字通信技术国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2007年第4期578-580,共3页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目(60272020)

摘　　要：在低速率声码器中,对激励信号的描述直接影响重建语音的质量。为了改善音质,引入了DCT-M模型对激励谱幅度参数进行描述,通过二维离散余弦变换将变长的谱幅度矢量转为固定长度,再对其进行多级矢量量化。测试表明,该方法能够保留全带激励谱幅度矢量的形状,降低模型误差,从而提高了全带激励谱幅度的描述精度。将其应用在正弦激励线性预测(SELP)声码器中进行测试,结果表明,它能够改善重建语音的自然度,主观测试结果达65%。The description precision of the excitation signal greatly influences the quality of reconstructed speech in low bitrate vocoders. In order to improve the reconstruction quality, DCT- M model is proposed to express the excitation spectral parameter, which transforms the variable length vector to fixed dimension through 2-dimensional DCT transformation, and then quantize the fixed length vector using multi-stage vector quantization. Tests show that the method maintains the shape of the entire spectral envelope, reduces model errors and thus greatly improves the description precision. In the sine excitation linear prediction （SELP） vocoder, the DCT M model improves the naturalness of the reconstructed speech, having subjective tests of 65 %.

关 键 词：声码器 DCT—M模型 模型误差 

分 类 号：TN912.32[电子电信—通信与信息系统]