Extract Voices from Music Signal
Implement 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. Add a spectrum view to the top two displays and the lower left display. 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 on 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.
Select the
high
signal by clicking its name in the Signal table. On the Analyzer tab, select Highpass from the Preprocessing gallery. On the Highpass tab that appears, enter a passband frequency of450
Hz and increase the steepness to0.95
. Click Highpass.Select the
medium
signal by clicking its name in the Signal table. On the Analyzer tab, select Bandpass from the Preprocessing gallery. On the Bandpass tab that appears, enter230
Hz and450
Hz as the lower and upper passband frequencies, respectively. Increase the steepness to0.95
. Click Bandpass.Select the
low
signal by clicking its name in the Signal table. On the Analyzer tab, select Lowpass from the Preprocessing gallery. On the Lowpass tab that appears, enter a passband frequency of230
Hz and increase the steepness to0.95
. Click Lowpass.
View a spectrogram on each of the three displays containing filtered signals.
Remove the original signal by clearing the check box next to its name.
On the Display tab, click Time-Frequency to add a spectrogram view and click Time to remove the time view.
On the Spectrogram tab, specify a time resolution of
0.31
second and0
% overlap between adjoining segments. Set the Power Limits to–50
dB and–10
dB.
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)
See Also
Apps
Functions
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More About
- Using Signal Analyzer App
- Edit Sample Rate and Other Time Information
- Data Types Supported by Signal Analyzer
- Spectrum Computation in Signal Analyzer
- Persistence Spectrum in Signal Analyzer
- Spectrogram Computation in Signal Analyzer
- Scalogram Computation in Signal Analyzer
- Keyboard Shortcuts for Signal Analyzer
- Signal Analyzer Tips and Limitations