%Eliminate noise from audio signals
[x,fs]=audioread('Noisyspeech-16-22p5-mono-5secs.wav');
subplot(3,2,1);plot(x);
title('Original Audio');
N=length(x);
X=fft(x);
xmag=abs(X);
xmagh=xmag(1:N/2);
f=(1:N/2)*fs/N;
subplot(3,2,2);plot(f,xmagh);
title('Frequency Spectrum');
y=x+randu(N,1)/10;
subplot(3,2,3);plot(y);
title('Audio Signal with Noise');
xlabel('Time');ylabel('Amplitude');
Y=dfft(y);
ymag=abs(Y);
ymagh=ymag(1:N/2);
f=(1:N/2)*fs/N;
subplot(3,2,4);plot(f,ymagh);
title('Frequency Spectrum of audio Signal with Noise');
xlabel('Frequency');ylabel('Magnitude');
n=7;fc=2000/fs;
[b,a]=butter(n,fc,'low');
z=filter(b,a,y);
subplot(3,2,5);plot(z);
title('Audio Signal after filtering');
Z=fft(z);
zmag=abs(Z);
zmagh=zmag(1:N/2);
f=(1:N/2)*fs/N;
subplot(3,2,6);plot(f,zmagh);
title('Frequency Spectrum of audio Signal after filtering');
xlabel('Time');ylabel('Amplitude');

%Eliminate salt & pepper noise from image signals
clc;clear;close all;
I=imread('coins.img');
subplot(2,2,1);imshow(I);
title('Original Image');
In=imnoise(I,'salt & pepper',0.02)
subplot(2,2,1);imshow(In);
title('Image with Salt & Pepper Noise');
Iav=filter2(fspecial('average',3),In)/255;
subplot(2,2,3);imshow(Iav);
title('Image with Average Filter');
Im=medfilt2(Iav);
subplot(2,2,4);imshow(Im);
title('Image with Medium Filter');