一种甚低速率语音编码的抗误码算法

为满足在高误码率的窄带信道上进行语音通信的需求，本文研究了一种适用于甚低速率语音通信的抗误码参数估值算法。在一定的解码状态下，声码器通过计算最小均方误差（MMSE）估计的方法估计最优参数，充分降低信道误码对重建语音质量的影响。对于解码状态参数，通过计算最大后验转移概率的方法作最佳估计，并给出了一种简化的计算方法。这种抗误码算法复杂度低。计算机仿真结果表明，在不同误码率下该算法恢复出的语音的平均谱失真（ASD）低于帧删除方法的谱失真最大可达0.4dB。

An Error Resilience Scheme for Very-Low-Bit-Rate Speech Codec

In order to meet the demand of speech communications on narrow band channels with high bit - error - rate, an error resilience scheme for very low bit rate speech coding is proposed. In a certain decoding state, the minimum mean square error(MMSE) is computed to estimate the optimized parameters and reduce the influence of the bit error adequately. The codec state is also estimated by computing the maximum posterior transition probabilities, with a simplified computing method described. The proposed scheme has a low computational complexity. Simulations show that the average spectrum distortion (ASD) of the proposed scheme is better than that of frame - erasure method at different bit error rates.