基于胞腔均匀度的清浊模式码书设计算法

清音和浊音线谱频率（LSF）参数分布具有差异性。为了提高声码器中LSF参数的量化性能，利用胞腔均匀度（CE）能定量表征清浊音LSF参数分布的差异程度，提出了一种基于CE的清浊模式码书设计算法。该算法首先根据CE推导出清音和浊音参与训练的LSF参数的数量比；然后剔除清音中指定数量的非典型LSF参数；最后重新训练出码书。实验结果表明，在相同码率情况下，该算法较码书共享算法谱失真降低2.5%，平均意见得分提高了2.3%，码书存储量下降了21.1%，并且适用于不传输清浊音标志的声码器。

Unvoiced/voiced mode codebook design algorithm based on cellular evenness

The parameter distribution of unvoiced/voiced Line Spectrum Frequency (LSF) has differences. In order to improve the quantization performance of LSF parameters in vocoder, an unvoiced/voiced mode codebook design algorithm based on Cell Evenness (CE) was presented by using the difference between unvoiced/voiced LSF parameters distribution and CE. Firstly, the optimal amount ratio of unvoiced/voiced LSF parameters participating in the codebook training was deduced according to CE. Then the specified number of atypia LSF parameters were eliminated from unvoiced speech. The final codebook was retrained. The experimental results show that, compared with the shared codebook algorithm under the same bit-rate condition, the average spectrum distortion of the proposed algorithm was reduced by 2.5%, the mean opinion score was increased by 2.3% and the storage of codebook was reduced by 21.1%. The proposed algorithm is also adapted to the vocoder without unvoiced/voiced symbol transmission and the algorithm is also adapted to the vocoder without unvoiced/voiced symbol transmission.