VoIP电话中的回声消除算法

声学回声是降低VoIP通话通信质量的重要问题之一，自适应回声抵消是抑制回声的最有效方法之一，其采用自适应滤波器评估回声路径。常用的NLMS(Normalized Least Mean Square)算法计算复杂度高，实用性差，本文利用FFT技术，实现了NLMS频域快速算法FDNLMS(Frequency Domain Normalized Least Mean Square)，将自适应更新变换到频域，逐块进行累加更新，保证收敛性能的同时，极大的降低了运算复杂度。实验表明，在滤波器系数为1024阶时，FDNLMS算法的处理速度比NLMS快12倍。

Echo Cancellation Algorithm in VoIP Phones

Acoustic echo is one of the most important problems to reduce the communication quality of VoIP calls. Adaptive echo cancellation is one of the most effective methods to suppress the echo. It uses an adaptive filter to evaluate the echo path. Commonly used NLMS(Normalized Least Mean Square) algorithm has high computational complexity and poor practicability. In this paper, the FFT technology is used to realize the frequency domain fast algorithm of NLMS-FDNLMS(Frequency Domain Normalized Least Mean Square), transform the adaptive update into the frequency domain, accumulate and update block by block .This algorithm guarantees convergence performance, while greatly reducing the computational complexity. Experiments show that FDNLMS algorithm can process 12 times faster than NLMS when the filter coefficient is 1024 order.