MATLAB语音信号的数字滤波

clear close all %读入音频信号 [xx,fs] = audioread('SunshineSquare.wav'); N = length(xx); n = 0:(N-1); %音频频域图 figure(1); w = n*2*pi/N; f = n*fs/N; xxSpectrum=abs(fft(xx,N)); plot(f,xxSpectrum); title('Freq. Waveform') xlabel('Freq.(Hz)') ylabel('Amp.') %音频时域图 figure(2); t = n/fs; plot(t,xx); title('Time Waveform') xlabel('Time(s)') ylabel('Amp.') yy = xx; %1575Hz滤波器 freqmax = 1575/fs B = -2*cos(freqmax*2*pi); hh = [1, B, 1]; yy = filter(hh, 1, yy); %3150Hz滤波器 freqmax = 3150/fs B = -2*cos(freqmax*2*pi) hh = [1, B, 1]; yy = filter(hh, 1, yy); %4725Hz滤波器 freqmax = 4725/fs B = -2*cos(freqmax*2*pi) hh = [1, B, 1]; yy = filter(hh, 1, yy); %写入新的音频信号 audiowrite('SunshineSquareNonoise.wav',yy,fs); %绘制观察其中的一个滤波器 ww = 0:pi/100:2*pi; HH = freqz(hh, 1 ,ww); figure(7); grid on subplot(2,1,1); plot(ww,abs(HH)); ylabel('20lg|H(jω)|(dB)') xlabel('Frequency-*π(rad)') title('Amplitude-Frequency Response') subplot(2,1,2); plot(ww,angle(HH)); ylabel('arg[H(jω)](rad)') xlabel('Frequency-*π(rad)') title('Phase-Frequency Response') %通过滤波器后音频信号频域图 grid on figure(3); xxSpectrumNonoise=abs(fft(yy,N)); plot(f,xxSpectrumNonoise); title('New Freq. Waveform 1') xlabel('Freq.(Hz)') ylabel('Amp.') %通过滤波器后音频信号时域图 grid on figure(4); t = n/fs; plot(t,yy); title('New Time Waveform 1') xlabel('Time(s)') ylabel('Amp.') %滤除直流分类 freqmax = 1/fs B = -2*cos(freqmax*2*pi) hh = [1, B, 1]; yy = filter(hh, 1, yy); %滤除冲击分量 for k = 1:N if yy(k)>=0.5 || yy(k)<=-0.5 yy(k) = 0; end end %额外处理后的音频信号频域波形 grid on figure(5); xxSpectrumNonoise=abs(fft(yy,N)); plot(f,xxSpectrumNonoise); title('New Freq. Waveform 2') xlabel('Freq.(Hz)') ylabel('Amp.') %额外处理后的音效信号时域波形 grid on figure(6); t = n/fs; plot(t,yy); title('New Time Waveform 2') xlabel('Time(s)') ylabel('Amp.') %写入新的音频文件 audiowrite('SunshineSquareImProved.wav',yy,fs); audiowrite('partspeech.wav',yy(1:55000),fs);