数字信号处理：用matlab实现音乐信号的滤波去噪

clear all;clc;close all;

[x,fs,bit]=wavread('F:\\费玉清-一剪梅 00_01_23-00_01_28.wav');

x=x(:,1);

% sound(x,fs);

N=length(x);

n=0:1/2048:1/2048*(N-1);

x1=cos(6000*pi*n)+cos(10000*pi*n)+cos(16000*pi*n);

x1=0.05*x1;

figure

subplot(2,1,1);plot(x1);

grid on

title('余弦混叠噪声时域波形')

xlabel('Time')

ylabel('Magnitude')

F1=fft(x1,N);

w=2/N*[0:N-1];

subplot(2,1,2);plot(w,abs(F1));

grid on

title('余弦混叠噪声频域波形')

xlabel('Frequency')

ylabel('Magnitude')

y1=x'+x1;

% sound(y1,fs);

figure

subplot(2,1,1);plot(y1);

grid on

title('音乐信号混叠噪声的时域波形')

xlabel('Time')

ylabel('Magnitude')

F2=fft(y1,N);

subplot(2,1,2);plot(w,abs(F2));

grid on

title('音乐信号混叠噪声的频域波形')

xlabel('Frequency')

ylabel('Magnitude')

Rp=0.5,Rs=10;

[N1,Wc]=buttord(0.015,0.02,Rp,Rs);

[B,A]=butter(N1,Wc);

[H,W]=freqz(B,A);

% Y1=filter(B,A,y1);

% % sound(Y1,fs);

% figure

% subplot(2,1,1);plot(Y1);

% grid on

% title('巴特沃斯滤波后时域波形')

% xlabel('Time')

% ylabel('Magnitude')

% F3=fft(Y1,N);

% subplot(2,1,2);plot(w,abs(Y1));

% title('巴特沃斯滤波后频域波形')

% xlabel('Frequency')

% ylabel('Magnitude')

r=rand(N,1);

x2=r-0.5;

figure

subplot(2,1,1);plot(x2);

grid on

title('随机白噪声时域波形')

xlabel('Time')

ylabel('Magnitude')

F3=fft(x2,N);

subplot(2,1,2);plot(w,abs(F3));

grid on

title('随机白噪声频域波形')

xlabel('Frequency')

ylabel('Magnitude')

y2=x+x2;

figure

subplot(2,1,1);plot(y2);

grid on

title('混叠随机白噪声音乐信号时域波形')

xlabel('Time')

ylabel('Magnitude')

F4=fft(y2,N);

subplot(2,1,2);plot(w,abs(F4));

grid on

title('混叠随机白噪声音乐信号频域波形')

xlabel('Frequency')

ylabel('Magnitude')

%sound(y2,fs);

Y2=filter(B,A,y2);

figure

subplot(2,1,1);plot(Y2);

grid on

title('巴特沃斯滤除随机白噪声后音乐信号时域波形')

xlabel('Time')

ylabel('Magnitude')

F5=fft(Y2,N);

subplot(2,1,2);plot(w,abs(F5));

grid on

title('巴特沃斯滤除随机白噪声后音乐信号频域波形')

xlabel('Frequency')

ylabel('Magnitude')

% sound(Y2,fs);

N2=33;wc=0.1*pi;

hd=ideal(N2,wc);

w1=blackman(N2);

h1=hd.*w1';

y3=conv(y1,h1);

y4=conv(y2,h1);

sound(y3,fs);

Y3=fft(y3,N);

Y4=fft(y4,N);

figure

subplot(2,1,1);plot(y3);

grid on

title('布莱克曼窗滤除预先噪声后音乐信号时域波形')

xlabel('Time')

ylabel('Magnitude')

subplot(2,1,2);plot(w,abs(Y3));

grid on

title('布莱克曼窗滤除预先噪声后音乐信号频域波形')

xlabel('Frequency')

ylabel('Magnitude')

% sound(y4,fs);

% figure

% subplot(2,1,1);plot(y4);

% grid on

% title('布莱克曼窗滤除随机白噪声后音乐信号时域波形')

% xlabel('Time')

% ylabel('Magnitude')

% subplot(2,1,2);plot(w,abs(Y4));

% grid on

% title('布莱克曼窗滤除随机白噪声后音乐信号频域波形')

% xlabel('Frequency')

% ylabel('Magnitude')