FFT SPEECH SIGNAL

clc;

clear;

close all

fs=20000

t=0:1/fs:.04;

x=4*sin(2*pi*2000*t)+4*sin(2*pi*1500*t)+10*sin(2*pi*6000*t)+6*sin(2*pi*200*t);

y=fft(x);

l=length(y);

Y=y(1:(l-1)/2);

r=1/((l-1)/2);

n=0:r:1-r;

plot(n,abs(Y)), xlabel('Normalized frq- 0 to corresponding for sampling rate 20KHz & 1rad=10KHz')

% speech_dft.wav

% toilet.wav

%% ACTUAL PROGRAM%%

clc

clear

[Y,FS,NBITS]=wavread('speech_dft.wav');

x=fft(Y);

l=length(x);

X=x(1:(l-1)/2);

r=1/((l-1)/2);

n=0:r:1-r;

subplot 211, plot(Y); subplot 212, plot(n,abs(X))

pause

% ½ of FS Hz corresponds to normalized 1 rad

%To remove 200Hz to 300Hz freq range % 2KHz is (2/FS)*200 rad % & 3KHz is (2/FS)*300 rad

rad_start=(2/FS)*200;

rad_stop=(2/FS)*300;

p_start=0;

for j=1:length(n)

if rad_start>=n(j)

p_start=j;

end

end

p_stop=0;

for j=1:length(n)

if rad_stop>=n(j)

p_stop=j;

end

end

Z=x;

for j=p_start:p_stop

Z(j)=0;

end

for j=l-p_stop:l-p_start

Z(j)=0;

end

subplot 211, plot(abs(x)); subplot 212, plot(abs(Z))

pause

y=ifft(Z);

subplot 211, plot(abs(Y));subplot 212, plot(abs(y))

wavwrite(y,FS,16,'processed_signal.wav');

wavwrite(y,FS,16,'original_signal.wav');