Extract Voices from Music Signal

mplement a basic digital music synthesizer and use it to play a traditional song in a three-voice arrangement. Specify a sample rate of 2 kHz. Save the song as a MATLAB® timetable.

fs = 2e3;
t = 0:1/fs:0.3-1/fs;

l = [0 130.81 146.83 164.81 174.61 196.00 220 246.94];
m = [0 261.63 293.66 329.63 349.23 392.00 440 493.88];
h = [0 523.25 587.33 659.25 698.46 783.99 880 987.77];
note = @(f,g) [1 1 1]*sin(2*pi*[l(g) m(g) h(f)]'.*t);

mel = [3 2 1 2 3 3 3 0 2 2 2 0 3 5 5 0 3 2 1 2 3 3 3 3 2 2 3 2 1]+1;
acc = [3 0 5 0 3 0 3 3 2 0 2 2 3 0 5 5 3 0 5 0 3 3 3 0 2 2 3 0 1]+1;

song = [];
for kj = 1:length(mel)
    song = [song note(mel(kj),acc(kj)) zeros(1,0.01*fs)];
end
song = song'/(max(abs(song))+0.1);

% To hear, type sound(song,fs)

tune = timetable(seconds((0:length(song)-1)'/fs),song);

Open Signal Analyzer and drag the timetable from the Workspace browser to the Signal table. Click Display Grid ? to create a two-by-two grid of displays. Select the top two displays and the lower left display and click the Spectrum button to add a spectrum view. Select the lower right display, click Time-Frequency to add a spectrogram view, and click Time to remove the time view. Drag the song to all four displays. Select the lower right display, and in the Spectrogram tab, specify a time resolution of 0.31 second (310 ms) and 0% overlap between adjoining segments. Set the Power Limits to −50 dB and −10 dB.

On the Analyzer tab, click Duplicate three times to create three copies of the song. Rename the copies as high, medium, and low by double-clicking the Name column in the Signal table. Move the copies to the top two and lower left displays.

Preprocess the duplicate signals using filters.

On each of the three displays containing filtered signals:

Select the three filtered signals by clicking their Name column in the Signal table. On the Analyzer tab, click Export and save the signals to a MAT-file called music.mat. In MATLAB, load the file to the workspace. Plot the spectra of the three signals.

load music

pspectrum(low)
hold on
pspectrum(medium)
pspectrum(high)
hold off

% To hear the different voices, type 
% sound(low.low,fs), pause(5), sound(medium.medium,fs), pause(5), sound(high.high,fs)