%語音信號采集、處理、傳輸、顯示
[y,fs,bite]=wavread('ma.wav',[1,520000]);
%采集語音信號
sound(y,fs,bite);
% sound(y,3*fs);
%回放語音信號
  figure(1);
   plot(y);  
    title('原語音信號時間幅度圖');
   [Y]=fft(y,409600);
   figure(2);
   plot(abs(Y));
   title('原語音信號頻譜圖');
        prompt={'輸入噪聲強度（標準差）','輸入持續時間/s'};
         titles='參數選擇';
         def={'0.08','5'};
         answer= inputdlg(prompt, titles, 1, def);
         var=str2num(answer{1});
         duration=str2num(answer{2});
         n=duration*fs;
         noise= var*randn(n,1);
         %sound(noise,fs,bite);
         len=length(y);
         lnoise=length(noise);
         if lnoise>len
             v=[y(:,1);zeros(abs(lnoise-len),1)];
             wave_change= v+ noise;
         else
             v=[noise(:,1);zeros(abs(lnoise-len),1)];
             wave_change= v+ y(:,1);
         end
     % sound(wave_change,fs,bite);  
      figure(3);
   plot(wave_change);   
     title('疊加噪聲的語音信號時間幅度圖');
[Y]=fft(wave_change,409600);
 figure(4);
plot(abs(Y));
 title('疊加噪聲的語音信號頻譜圖');
 %sound(wave_change,3*fs);