% wavelets.m reads the data file wavelets.wav and plays it

[w]=wavread('wavelets.wav');      % read "wavelets" data file
[a]=wavread('a.wav');


sound(w,44100);                   % play back the sound

figure(1);

subplot(2,1,1);

n=size(w);
w=w-median(w);
t=(1:n)/44100;
plot(t,w);

title('Signal from spoken word');
xlabel('Time in seconds (sampled 44,100 times per second)');
ylabel('Signal (integer values)');

subplot(2,1,2);

n=size(a);
a=a-median(a);
t=(1:n)/44100;
plot(t,a);

title('Signal from spoken vowel');
xlabel('Time in seconds (sampled 44,100 times per second)');
ylabel('Signal (integer values)');

figure(2);

subplot(2,1,1);
ws = fft(w);
k=[1:1:900];
plot(k,abs(ws(k))/5000);
ylabel('Strength');
xlabel('Frequency (cycles per second)');
title('Fourier energy spectrum of the word "wavelets"');


subplot(2,1,2);
as = fft(a);
plot(k,abs(as(k))/5000);
ylabel('Strength');
xlabel('Frequency (cycles per second)');
title('Fourier energy spectrum of the spoken "a"');