You are here: Home Manual Chapter 3: Spectral Analysis Setting the Spectral Parameters

Setting the Spectral Parameters

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SAP2011 supports sounds digitized at any rate, including ultra sound. The frequency range is adjustable in this version to 3 ranges: full spectral range (sampling rate/2, which is as high as frequency analysis can go), half range, or quarter range.

You can change the contrast of the derivative display without changing the contrast of the feature curves by moving the Gain slider on the left.

Figure 1: Contrast slider at the minimum
Fig 2: Contrast slider at the maximum

This manipulation has only visual effect.

If however, the sounds you are analyzing are of very low amplitude (e.g., forcing you to increase the display gain all the way up), you may want to boost them prior to analysis.
You can do this by going to the Display & Settings tab > check "boost sound amplitude". Be aware though, that this might virtually “clip” sounds of high amplitude.

Note that changing the amplitude of wave files data should have no effect on song features except for amplitude of course, as long as data are not clipped (namely, as long as the numbers are within the 16bit range).

Spectral parameters

There are 4 parameters that you can change within the ‘Explore & Score’ module, the Frequency range, FFT data window, Advance window and Contour threshold.
Be aware that the scope of those changes is global – that is all other modules will apply this change.

Figure 3: Four parameters that you can change within the ‘Explore & Score’ module
Start by changing the size of the FFT data window. Reducing it to 5ms, and reopening the sound will present a different time-frequency compromise. Note that feature calculation & scale are affected by such manipulation.

Return the data window size to 9.27ms, and change the advance window to 0.4ms, and sound display, as well as feature calculation, becomes more elaborate. The only feature that will change scale is AM: Try identifying and comparing the first two syllables across the two displays. Change the advance window back to 1.2ms.