Notes

function xx = key2note(X, keynum, dur)

fs = 11025;
tt = 0:(1/fs):dur;
freq = 440 * 2^((keynum - 49) / 12);
xx = real(X * exp(1j * 2 * pi * freq * tt));
disp(freq);
end



X = 1 * exp(1j * 0); % Complex amplitude (magnitude 1, phase 0)
keynum = 40; % Piano key number for middle C
dur = 2; % Duration of the note in seconds

xx = key2note(X, keynum, dur);



scale.keys = [ 40 42 44 45 47 49 51 52 ];

% NOTES: C D E F G A B C
% key #40 is middle-C
scale.durations = 0.25 * ones(1,length(scale.keys));
fs = 11025;% or 8000 Hz
xx = zeros(1, sum(scale.durations)*fs+length(scale.keys) );
n1 = 1;
X=1*exp(1j*0);
for kk = 1:length(scale.keys)
keynum = scale.keys(kk);
dur = scale.durations(kk);
tone = key2note(X,keynum,dur); %<=== FILL IN THIS LINE
n2 = n1 + length(tone) - 1;
xx(n1:n2) = xx(n1:n2) + tone; %<=== Insert the note
n1 = n2 + 1;
end
soundsc( xx, fs )

figure;
specgram(xx, 512, fs);
title('Spectrogram of Synthesized Scale with Window Length 512');
xlabel('Time (seconds)');
ylabel('Frequency (Hz)');

% Spectrogram with window length 1024
figure;
specgram(xx, 1024, fs);
title('Spectrogram of Synthesized Scale with Window Length 1024');
xlabel('Time (seconds)');
ylabel('Frequency (Hz)');