数字信号处理实验报告--含噪语音信号的分析

大连理工大学实验报告
实验四含噪语音信号的分析
一实验代码及程序
利用callback在.m文件中对各个模块进行代码的编辑（下面列出主要部分）：1、输入音频信号部分：
[filename,filepath]=uigetfile('.wav','选择音频文件');
if(filename==0)
return;
end
audeofile= strcat(filepath,filename);
[handles.tdata,fs,handles.NBITS]=wavread(audeofile);
%绘制时域波形图
t = [0:1/fs:(length(handles.tdata)-1)/fs];%信号的时域长度
subplot(handles.fig1);
plot(t, handles.tdata);
%绘制频谱图
N = length(t);
fftdata = fft(handles.tdata,N);
fdata = abs(fftdata);
df = fs / N;
f = [0 : df : df * (N - 1)] - fs / 2;%求频率
subplot(handles.fig2);
plot(f, fftshift(fdata) );
guidata(hObject, handles);
2、设置低通部分：
function pushbutton4_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton4 (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDA TA)
fp=str2num(get(handles.edit1,'string'));
fr=str2num(get(handles.edit2,'string'));
Ap=str2num(get(handles.edit3,'string'));
Ar=str2num(get(handles.edit4,'string'));
wp=2*pi*fp/1000;
wr=2*pi*fr/1000;
%Ap=3;
%Ar=20;
Ts=1/1000;
Op=2/Ts*tan(wp/2);
Os=2/Ts*tan(wr/2)
[N,Wn]=buttord(Op,Os,Ap,Ar,'s');
[z,p,k]=buttap(N)
[b,a]=zp2tf(z,p,k);
[B,A]=lp2lp(b,a,Wn);
[Bz,Az]=bilinear(B,A,1000);
[f,w]=freqz(Bz,Az);
f_mag=abs(f);
f_ang=angle(f);
%subplot(2,1,1); plot(w/pi,abs(f_mag));
%subplot(2,1,2); plot(w/pi,20*log(abs(f_mag)));
%N = length(t);
%fftdata = fft(handles.tdata,N);
%fdata = abs(w);
%df = fs / N;
%f = [0 : df : df * (N - 1)] - fs / 2;%求频率
subplot(handles.fig3);
plot(w/pi, f_mag );
guidata(hObject, handles);
y = filtfilt(Bz,Az,handles.tdata);
handles.tdata=y;
%绘制时域波形图
fs=1000;
t = [0:1/fs:(length(handles.tdata)-1)/fs];%信号的时域长度
subplot(handles.fig4);
plot(t,handles.tdata);
%绘制频谱图
N = length(t);
fftdata = fft(handles.tdata,N);
fdata = abs(fftdata);
df = fs / N;
f = [0 : df : df * (N - 1)] - fs / 2;%求频率
subplot(handles.fig5);
plot(f, fftshift(fdata) );
guidata(hObject, handles);
3 设置高通部分
function pushbutton6_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton6 (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDA TA) fp=str2num(get(handles.edit1,'string'));
fr=str2num(get(handles.edit2,'string'));
Ap=str2num(get(handles.edit3,'string'));
Ar=str2num(get(handles.edit4,'string'));
Ts=1/1000;
wp=2*pi*fp*Ts;
wr=2*pi*fr*Ts;
%Ap=3;
%Ar=20;
[N,Wn]=buttord(wp/pi,wr/pi,Ap,Ar);
[b,a]=butter(N,Wn,'high');
[f,w]=freqz(b,a);
f_mag=abs(f);
f_ang=angle(f);
%subplot(2,1,1); plot(w/pi,abs(f_mag));
%subplot(2,1,2); plot(w/pi,20*log(abs(f_mag)));
%N = length(t);
%fftdata = fft(handles.tdata,N);
%fdata = abs(w);
%df = fs / N;
%f = [0 : df : df * (N - 1)] - fs / 2;%求频率
subplot(handles.fig3);
plot(w/pi, f_mag );
guidata(hObject, handles);
y = filtfilt(b,a,handles.tdata);
handles.tdata=y;
%绘制时域波形图
fs=1000;
t = [0:1/fs:(length(handles.tdata)-1)/fs];%信号的时域长度subplot(handles.fig4);
plot(t,handles.tdata);
%绘制频谱图
N = length(t);
fftdata = fft(handles.tdata,N);
fdata = abs(fftdata);
df = fs / N;
f = [0 : df : df * (N - 1)] - fs / 2;%求频率
subplot(handles.fig5);
plot(f, fftshift(fdata) );
guidata(hObject, handles);
GUI界面
初始界面
低通滤波
高通滤波
二、实验建议与体会
本次实验的题目是含噪语音信号分析。

在实验过程中，排版出现了一定的问题，导致结果无法显示。

经过排查之后，程序结果可以顺利求
出。

最重要的是在实验过程中明确了设置截止频率的重要性，如果不设置，会导致程序无法运行。