音频信号去噪

Question

下面的人是我的密码。我想消除噪音，从音频信号，我自己加起来，使用随机的function.The，下面的代码消除了一些噪音，但它仍然太吵，我无法听到声音。我还想为这段代码添加音频文件，但我在发布问题时没有找到任何选项，所以您可以添加任何两个频道的.wav声音文件。任何评论或暗示都会有帮助，谢谢。

close all
clear 
clc 


[x,fs] = audioread('cello.wav');             
whos x;                                         
 pOrig = audioplayer(x,fs);                %Signal Play
 pOrig.play;

N = size(x,1);                            
figure;
subplot(2,1,1);
stem(1:N, x(:,1));
title('Left Channel of Origional signal');
subplot(2,1,2);
stem(1:N, x(:,2));
title('Right Channel of origional signal');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 df = fs/N;
 w = (-(N/2):(N/2)-1)*df;
 y1= fft(x(:,1),N)/N;
 y2 = fftshift(y1);
 figure;
 plot(w,abs(y2));
title('Fast Fourier Transform of Origional Signal')

   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
pause
 y=x;
 y = y + randn(size(y));
 pOrig = audioplayer(y,fs);
 pOrig.play;

figure;
subplot(2,1,1);
stem(1:N, y(:,1));
title('Left Channel with Noise');  
subplot(2,1,2);
stem(1:N, y(:,2));
title('Right Channel with Noise');                     




 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 df = fs/N;
 w = (-(N/2):(N/2)-1)*df;
 y1= fft(y(:,1),N)/N;
 y2 = fftshift(y1);
 figure;
 plot(w,abs(y2));
 title('Fast Fourier Transform of Noisy Signal')
 pause  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% filter design 
 n = 10;
beginFreq = 100 / (fs/2);
endFreq =  2000  / (fs/2);
%[b,a] = butter(n,  endFreq, 'low');
%fout = filter(b,a,y);                         % input y(noisy signal)

[b,a] = butter(n,  endFreq, 'low');
fout = filter(b,a,y);                         % input y(noisy signal)



figure;
subplot(2,1,1);
stem(1:N, fout(:,1));
title('Left channel after filtering');  
 subplot(2,1,2);
 stem(1:N, fout(:,2));
 title(' Right channel after filtering');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%plot(fout); 

 df = fs/N;
 w = (-(N/2):(N/2)-1)*df;
 y1= fft(fout(:,1),N)/N; 
 y2 = fftshift(y1);
 figure;
 plot(w,abs(y2));
title('Fast Fourier Transform  after filtering');

 pOrig = audioplayer(fout,fs);
 pOrig.play;

Answer 1

你是用随机()函数来增加噪声，它产生高斯噪声，即白噪声。白噪声在频谱上有恒定的功率，这意味着你要增加从0到20 The的噪声(仅考虑音频频谱)。

你的滤波器是一个在0.1到2 kHz之间的带通滤波器，所以根据我上面指出的，在这些频带中仍然有噪声成分。理论上，它是不可能过滤所有的噪声成分，但你可能想要检查维纳滤波器，以获得更好的结果。实际上，如果你知道高斯噪声参数，它就是最优滤波器，在你的情况下，这只是噪声的方差。

如果你想看到一个消除所有噪音的例子，你可以把带外噪声加到你的原始信号上。通过rand()生成随机序列并使用过滤器使其带宽受限，这是可能的。例如，用3-10 the的带通滤波器过滤产生的噪声序列，然后添加到原始音频序列中。最后，在脚本中应用相同的黄油过滤器来查看所有的噪音都被消除了。