2.4 kb/s MELP算法设计

提出了一种新的工作于低极码率下的混合激励线性预测（ＭＥＬＰ）声码器。该声码器结合了线性预测编码（ＬＰＣ）和多带激励编码算法的优点，对算法和量化方案重新进行了设计和改造，其主要特征包括改进的基音检测算法、混合的周期脉冲和随机噪声激励，有效的线性谱频率（ＬＰＦ）参数量化以及激励谱形状表示，非正式主观测试表明，由采用本算法的一个２．４ｋｂ／ｓ编码器所重建的语音质量略优于美国联邦标准４．８ｋｂ／ｓ码激励性

New Mixed Excitation Linear Prediction Codec at 2.4 kb/s

A new mixed excitation linear prediction(MELP) codec working at very low bit rate was presented. This codec utilizes the advantages of both linear prediction coding(LPC) algorithm and multiband excitation(MBE) coding algorithm. In order to get natural speech with good quality, some new features of the algorithm and quantization scheme were employed including robust pitch detection algorithm, mixed excitation detemination, efficient linear spectred frequency(LSF) parameter quantization, and new excitation spectrum expression. Informal subjective testing shows the quality of speech synthesized by a 2.4 kb/s codec using this MELP algorithm is a little better than or same as that synthesized by FS1016 4.8 kb/s CELP.