说明：  基于Matlab的音频文件数字滤波处理。本文基于Matlab分析了wav声音文件频谱与声音的关系，并给出了不同采样频率对输出声音信号的影响。
(Matlab-based digital filter processing of audio files. This analysis based on Matlab wav sound files and sound relationship between the spectrum and gives different output sampling frequency of the sound signals.)