MATLAB realizes voice signal resampling and normalization, and plays the comparison effect

On the basis of the previous sections , Carry out the experiment in this section .
Recommended reading ：
matlab Use audiorecorder、recordblocking Recording sound ,play The play ,audiowrite Save sound
matlab Use audioread 、 sound Read and play wav file
matlab Use resample Complete resampling

Be careful ：
Used this time wav The length of the file is 5 second , So a few lines of my code are written pause(6); The purpose is to make the sound still have 1 Seconds of spare time , Let's play the next sound .
I'm using matlab2018a, So in this version wavread The function has been abandoned , I can only use audioread function .
If you don't wav Voice files , You can refer to the first blog recommended to read and make one by yourself , Very convenient .

% Speech signal sampling frequency conversion experiment 
clc
clear all
%[x,fs1]=wavread('C2_2_y.wav');% wavread  The function has been abandoned 
[x,fs1]=audioread('C2_2_y.wav');%matlab2018a, have access to  audioread  This function 

s1=1:length(x);
t1=s1/fs1;
xmax=max(abs(x));% Get all sample The absolute value of the maximum value of 
x=x/xmax;% take wav Every one of the files sample Value divided by the largest sample value , Make all of x All in [-1,1] Within the interval , Complete normalization 

figure(1)
subplot(311)
plot(t1,x);
xlabel(' Time /s');
ylabel(' Normalized amplitude ');
title('(a) The original signal ');
sound(x,fs1);
pause(6);% Because the voice time played is 5 second , So the interval here 6 second , So that it can be played next time , Otherwise, the three sounds will overlap 

%2 Double resampling 
p=2;q=1;
x1=resample(x,p,q);% Resampling signal , Make the number of elements of the signal double 
x1max=max(abs(x1));
x1=x1/x1max;% normalization 
fa=fs1*p/q;% The frequency of the signal after resampling , That is to say   The frequency of the original signal  *  Multiple of resampling 
ta=(1:length(x1))/fa;% Time coordinates of each signal after resampling 
subplot(312);
plot(ta,x1);
sound(x1,fa);
pause(6);% Because the voice time played is 5 second , So the interval here 6 second , So that it can be played next time , Otherwise, the three sounds will overlap 

xlabel(' Time /s');
ylabel(' Normalized amplitude ');
title('(b)2 Times the sampling rate ');

%0.5 Double resampling 
p=1;q=2;
x2=resample(x,p,q);
x2max=max(abs(x2));
x2=x2/x2max;
fb=fs1*p/q;
tb=(1:length(x2))/fb;
subplot(313);
plot(tb,x2);
xlabel(' Time /s');
ylabel(' Normalized amplitude ');
title('(c)1/2 Sampling rate ');
sound(x2,fb);