音乐信号的处理 matlab

1、1、音乐信号的音谱和频谱观察y,fs,bit=wavread('2');sound(y,fs);plot(y);y1=y(:,1);M=512;fh1=fft(y1,M);w=2/M*0:M-1;figure;plot(w,abs(fh1);2、音乐信号的抽取（减抽样）y,fs,bit=wavread('2');sound(y,fs);figure;subplot(1,2,1);plot(y);title('原音乐信号波形');y1=y(:,1);M=512;fh1=fft(y1,M);w=2/M*0:M-1;subplot(1,2,2);plo

2、t(w,fh1);title('原音乐信号频谱');grid on;j=0;d=10; %减抽样间隔 取3和10 代表混叠与非混叠 y3=y1(1:100000); for i=1:d:length(y3); j=j+1; yd(j)=y1(i); endsound(yd,fs/d); figure;subplot(1,2,1);plot(yd);title('减抽样时域');fh2=fft(yd);l1=length(fh2);w2=2/l1*(0:l1-1);subplot(1,2,2);plot(w2,abs(fh2);title('减抽样频域&#

3、39;);3、音乐信号的AM调制和巴特沃斯IIR滤波器滤波w,fs,bit=wavread('2');w1=w(:,1);l=length(w1);ww=2/l*(0:l-1);n=0:length(w1)-1;t1=w1.*cos(0.6*pi*n)' T1=fft(t1);plot(t1);title('AM低/高频调制后波形');figure;plot(ww,abs(T1);title('AM低/高频调制后频谱');sound(t1,fs);t2=t1.*cos(0.6*pi*n)'T2=fft(t2);figure;plo

4、t(t2);title('AM低/高频解调后波形');figure;plot(ww,abs(T2);title('AM低/高频解调后频谱');sound(t2,fs);N,wc=buttord(0.2,0.3,2,15); b1,a=butter(N,wc);h,wi=freqz(b1,a);figure;plot(wi/pi,abs(h);title('iir滤波器频谱');%用iir对信号滤波y=filter(b1,a,t2);Y=fft(y);figure;plot(y);title('低/高频解调滤波后时域');figur

5、e;plot(ww,abs(Y);title('低/高频解调滤波后的频域');sound(y,fs);用窗函数法设计FIR滤波器（矩形窗和布莱克曼窗）w,fs,bit=wavread('2');w1=w(:,1);n=0:length(w1)-1;t1=w1.*cos(0.6*pi*n)' j1=t1.*cos(0.6*pi*n)'%用FIR对信号同步解调N=55;wc=pi/4;% boxcar N取9hd=ideal(N,wc);w=blackman(N);%blackman和boxcarh=hd.*w'M=512;fh=fft(h,

6、M);ww=2/M*(0:M-1);plot(ww,abs(fh);title('矩形窗fir滤波器频率响应');y=conv(j1,h);Y=fft(y,M);figureplot(y);title('矩形窗fir滤波后时域');figureplot(ww,abs(Y);title('矩形窗fir滤波后频域');sound(y,fs);三余弦和白噪声的实验y,fs,bit=wavread('2');y1=y(:,1);f=fft(y1);l=length(f);ww=2/l*(0:l-1);n=0:length(y1)-1;x=

7、0.05*(cos(2*pi*3000*n/fs)+cos(2*pi*5000*n/fs)+cos(2*pi*8000*n/fs);fx1=fft(x);plot(ww,abs(fx1);title('三余弦噪声频谱');r=rand(size(y1),1)-0.5;fx2=fft(r);figureplot(ww,abs(fx2);title('随机白噪声频谱');x1=y1'+x;figureplot(x1);title('加三余弦噪声的信号音谱');fx3=fft(x1);figureplot(ww,abs(fx3);title(&

8、#39;加三余弦噪声的信号频谱');x2=y1+r;figureplot(x2);title('加白噪声的信号音谱');fx4=fft(x2);figureplot(ww,abs(fx4);title('加白噪声的信号频谱');sound(x1,fs);sound(x2,fs);三余弦噪声滤波y,fs,bit=wavread('2');y1=y(:,1);f=fft(y1);l=length(f);ww=2/l*(0:l-1);n=0:length(y1)-1;x=0.05*(cos(2*pi*3000*n/fs)+cos(2*pi*50

9、00*n/fs)+cos(2*pi*8000*n/fs);fx1=fft(x);plot(ww,abs(fx1);title('三余弦噪声频谱');x1=y1'+x;figureplot(x1);title('加三余弦噪声的信号音谱');fx3=fft(x1);figureplot(ww,abs(fx3);title('加三余弦噪声的信号频谱');sound(x1,fs);N,wc=buttord(0.1,0.14,5,20);b1,a=butter(N,wc);R=filter(b1,a,x1);fr=fft(R);figureplot

10、(R);title('滤波去噪后信号的音谱');figureplot(ww,abs(fr);title('滤波去噪后信号频谱');sound(R,fs);随机白噪声滤波y,fs,bit=wavread('2');y1=y(:,1);f=fft(y1);l=length(f);ww=2/l*(0:l-1);n=0:length(y1)-1;r=rand(size(y1),1)-0.5;fx2=fft(r);figureplot(ww,abs(fx2);title('随机白噪声频谱');x2=y1+r;figureplot(x2);t

11、itle('加白噪声的信号音谱');fx4=fft(x2);figureplot(ww,abs(fx4);title('加白噪声的信号频谱');N,wc=buttord(0.06,0.1,2,20);b1,a=butter(N,wc);G=filter(b1,a,x2);fg1=fft(G);figureplot(G);title('滤波去噪后信号的音谱');figureplot(ww,abs(fg1);title('滤波去噪后信号频谱');sound(x2,fs);sound(G,fs);设计低通滤波器y,fs,bit=wavr

12、ead('2');y1=y(:,1);fx1=fft(y1);l=length(fx1);ww=2/l*(0:l-1);figure;plot(ww,abs(fx1);title('原信号频谱');N,wc=buttord(0.1,0.15,1,20); b1,a=butter(N,wc);h,wi=freqz(b1,a);figure;plot(wi/pi,abs(h);title('滤波器特性曲线');y=filter(b1,a,y1);fx2=fft(y);figure;plot(ww,abs(fx2);title('滤波后频谱&#

13、39;);sound(y1,fs);sound(y,fs);设计高通滤波器y,fs,bit=wavread('1');y1=y(:,1);fx1=fft(y1);l=length(fx1);ww=2/l*(0:l-1);figure;plot(ww,abs(fx1);title('原信号频谱');N,wc=buttord(0.15,0.2,1,20); b1,a=butter(N,wc,'high');h,wi=freqz(b1,a,'whole');figure;plot(wi/pi,abs(h);title('滤波器特性曲线');y2=filter(b1,a,y1);fx2=fft(y2);figure;plot(ww,abs(fx2);title('滤波后频谱');sound(y1,fs);sound(y2