设计音频降噪算法，并用MATLAB仿真实现。

1）读入一段音频后添加噪声，必须包括两种不同的噪声，信噪比：0dB~10dB；

2）分别采用滑动平均滤波器，直接频域滤波，以及谱分析后设计滤波器滤波三种方法实现，并对比效果。

3）给出各种方案的设计依据、代码、频响曲线，以及输入输出对比图。-Audio noise reduction algorithm design, and use MATLAB Simulation.

1) Read after adding noise into an audio, it must include two different kinds of noise, SNR: 0dB ~ 10dB

2) respectively moving average filter directly in the frequency domain filtering, and the filter is designed to achieve three methods filter after spectral analysis and contrast.

3) Give the design basis, code, frequency response curve, and input and output comparison chart of the various programs.