Sound Analysis
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0
0.01
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0.1
time [seconds]
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frequency [Hz]
-14
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[dB]
Figure 7: 3D STFT representation of the signal (15). N = 128 and R = 64.
imagesc(flipud(log(S)));
# display in log scale
mesh(t,f(1:length(f)-1),log(S));
gset view 35, 65, 1, 1.2
xlabel('time [seconds]');
ylabel('frequency [Hz]');
zlabel('[dB]');
replot;
In this example, the DFT length has been set to N = 128, the analysis
window is a Hann window with length R = 64, and the hop size to R/2. If the
window length is doubled, the two components separate much more clearly, as
shown in figure 8.
4.1.5
Accurate partial estimation
If the signal under analysis has a sinusoidal component that stays in between
two adjacent DFT bins, the magnitude spectrum is similar to that reported in
figure 9. We notice the two following phenomena: