基于MMSE的声码器解码算法

为满足在高误码率的窄带信道上进行语音通信的需求 ,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。基于一定的解码状态 ,声码器通过最小均方误差(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估计方法。这种抗误码算法计算量小 ,算法复杂度低。仿真结果表明 ,在不同误码率下用该算法恢复出的重建语音 ,不论客观评价或是主观评价 ,其质量都要优于传统的帧删除掩盖方法

Decoding algorithm based on MMSE for speech codec

An error resilience scheme for very low bit rate speech coding was developed for speech communications on narrow band channels with high bit error rates. The minimum mean square error (MMSE) is computed for each decoding state to estimate optimal parameters and to reduce the influence of the bit error. The codec states were estimated by computing the maximum posterior transition probabilities with a simplified computing method. The proposed scheme requires less computations and is less complex than previous methods. Objective and subjective simulations show that the performance of the proposed scheme is always better than that of the frame erasure method at all bit error rates.