首先提取语音信号，并对其加单频噪声，设计IIR滤波器，滤除单频噪声，显示滤除前后时域波形的对比，并播放滤除后的语音信号。-First, extract the speech signal, and add single-frequency noise, design IIR filters to filter out single-frequency noise. Display the time-domain　 waveform before and after filter, and play the voice signal after filtering.