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DIGITAL SIGNAL PROCESSING
Lab Session 3: Audio Processing.
Objective
Audio Processing Basics in MATLAB To study effect of adding
noise to any voice signal.
Load a voice file already present in MATLAB using the following
command:
>>load mtlb
You mayplay the file using the soundsc function.
How many voice samples are contained in the mtlb file?
4001
Create a random row vector of the same size as the mtlb signal
above using the randn function.
Now add the two vectors (the one generated using the randn
function and the one obtained using
mtlb). The sum of these two signals is the corrupted signal.
Plot all the signals obtained, your
plot should show the uncorrupted signal; the noise vector
generated using randn function and
the corrupted signal. Write code in the space provided below.
(you might want to hear andcompare sound quality)
Code & Figure:
load mtlb;
soundsc(mtlb);
x=mtlb;
z=randn(size(x));
[y,n]=sigadd(x,z,size(x),size(z));
subplot(311),plot(n,x)
subplot(312),plot(n,z)
subplot(313),plot(n,y)
soundsc(y);
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Sinusoidal Sequence: Plot the following functions in a plot of
3x3 subplots:
f(t) = exp(k*t) * sin(2*PI*f*t)
t = [0, 1] in steps of 0.0001
k = -3, 0, 3
f = 1, 3, 6 Hz
Code:
a=1;
t = [0:0.0001:1]; %in steps of 0.0001
fl=[1 3 6];
kl=[-3:3:3];
for f=[1 3 6]
for k=-3:3:3func=exp(k*t).*sin(2*pi*f*t);
subplot(length(kl),length(fl),a),plot(t,func);
a=a+1;
end
end
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Figure:
Use the soundsc function in MATLAB to hear the tones produced by
each function. Describe the
relation of the intensity and pitch of the tones to the
amplitude and frequency of the function.
Intensity of the function is increased by increasing amplitude
of the function and vice versa.
Pitch of the function is increased by increasing frequency of
the function and vice versa.
The echo, y(n), of a discrete signal, x(n), of lengthN, may be
modeled as a repeated and scaled
version of the original signal. Write a function that generates
an echo of an argument signal, withthe repeated signal scaled down
by an argument factor.
0 0.5 1-0.5
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function y = echogen (x, u, n)
% Generates an echoing version of input signal
% x : original signal
% u : scaling factor of the intensity of each% repeated signal:
the intensity of i-th
% (1
