% spectra.m displays the spectra of some notes, chords, and spoken sounds

p=2^(1/12);                        % frequency multiplier between notes
t=1:44100;                         % vector of time indices
a =sin(440*2*pi*t/44100);          % define an a
as=sin(440*(p^1)*2*pi*t/44100);
b =sin(440*(p^2)*2*pi*t/44100);
c =sin(440*(p^3)*2*pi*t/44100);
cs=sin(440*(p^4)*2*pi*t/44100);
d =sin(440*(p^5)*2*pi*t/44100);
ds=sin(440*(p^6)*2*pi*t/44100);
e =sin(440*(p^7)*2*pi*t/44100);
f =sin(440*(p^8)*2*pi*t/44100);
fs=sin(440*(p^9)*2*pi*t/44100);
g =sin(440*(p^10)*2*pi*t/44100);
gs=sin(440*(p^11)*2*pi*t/44100);
a2 =sin(440*(p^12)*2*pi*t/44100);  % a one octave up
a3 =sin(440*(p^24)*2*pi*t/44100);  % another octave up

a_spectrum = fft(a);               % spectrum is the fast Fourier transform
a_spectrum(1)=1;

chord=a+cs+e;
chord = chord/(max(abs(chord)));
chord_spectrum = fft(chord);
chord_spectrum(1)=1;

[sa]=wavread('a.spoken.out');      % read spoken a data
sa_spectrum=fft(sa);
sa_spectrum(1)=1;
[se]=wavread('e.spoken.out');      % read spoken e data
se_spectrum=fft(se);
se_spectrum(1)=1;
[so]=wavread('o.spoken.out');      % read spoken o data
so_spectrum=fft(so);
so_spectrum(1)=1;
[su]=wavread('oo.spoken.out');     % read spoken oo data
su_spectrum=fft(su);
su_spectrum(1)=1;

ind=1:(44100/20);                      % indices
t=ind/44100;                       % rescale to be time in seconds

subplot(4,2,1)
plot(t,a(ind));
title('Pure A (440 Hz)');
axis([0 0.05 -1.2 1.2]);
xlabel('Time');
ylabel('Speaker cone location');

subplot(4,2,2)
plot(t,chord(ind));
title('A-C#-E chord (440, 554, 659 Hz)');
axis([0 0.05 -1.2 1.2]);
xlabel('Time');
ylabel('Speaker cone location');

k=[1:1:900];                       % vector of frequencies to plot

subplot(4,2,3)
plot(k,abs(a_spectrum(k))/5000), text(600,4.5,'Pure A')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for pure A');

subplot(4,2,4)
plot(k,abs(chord_spectrum(k))/5000), text(600,1.2,'A-C#-E chord')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for A-C#-E chord');

subplot(4,2,5)
plot(k,abs(sa_spectrum(k))/5000), text(600,125,'Spoken a')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for spoken long A');

subplot(4,2,6)
plot(k,abs(se_spectrum(k))/5000), text(600,70,'Spoken e')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for spoken long E');

subplot(4,2,7)
plot(k,abs(so_spectrum(k))/5000), text(600,50,'Spoken o')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for spoken long O');

subplot(4,2,8)
plot(k,abs(su_spectrum(k))/5000), text(600,80,'Spoken oo')
ylabel('Strength');
xlabel('Frequency');
title('Frequency spectrum for spoken OO');

orient tall
print -deps spectra.eps