一种低速率多模MBE线性预测语音编解码器

提出了一种多模多带激励(MBE)线性预测语音编解码器，与MBE编解码器相比在两个方面有所改进:一是在频谱幅度估计中结合了线性预测的方法，幅度的线性预测结果用线谱频率(LSF)来表示并量化，解决了原系统频谱幅度量化中维数变化的问题; 二是在清/浊音判决中，固定每帧中子带的个数，划分不同的清/浊音判决模式，在各种清/浊音判决模式下，根据LSF不同的统计特性，用不同的码本对LSF矢量进行量化，提高了量化的质量．仿真结果显示，合成语音可懂度高，时域语音波形图及语谱图都拟合较好．

Low rate multimode MBE vocoder with linear prediction coding

This paper presents a model of the Multimode Multi-Band Excitation (MBE) joined with the Linear Prediction vocoder. Compared with MBE coding, this vocoder has some improvements in two ways. First, the Linear Predictive Mode is combined with Spectrum Estimation, and then the linear predictive coefficients are denoted and quantized by Line Spectral Frequency parameters (LSF), which solves the problem of variable dimensions in spectrum estimation in the MBE system. Second, in Unvoiced/Voiced (U/V) Decision, the number of sub-bands in one frame is fixed, ahd then the decisions are divided into different modes. LSF vectors are quantized by different codebooks to improve the quantization result, according to the different statistic distributions of the LSF vector in different U/V determinative modes. Simulation by the C programming language demonstrates that the synthesized speech Intelligibility is high and that the speech waveforms in the time domain and spectrograms both fit well.