3.2.1.4.3. Non-tonal components

One non-tonal component for each critical subband is extracted from the remaining spectral lines. Amplitude of non-tonal components - similar to noise - is computed by adding together all spectral lines that are not part of tonal components in the critical band interval z(k), whose frequency bounds are precomputed in a table.

for each j belonging to critic_band(k)

In practice, the audible spectrum is subdivided as follows:

LAYER	SAMPLING FREQUENCY	NUMBER OF CRITICAL BANDS
I	32.0 KHz	23
	44.1 KHz	24
	48KHz	25
II	32.0 KHz	24
	44.1 KHz	26
	48KHz	26

In each subband, power amplitudes of the spectral lines are added together, obtaining the component which is considered non-tonal. Its spectral location is found from the spectral line which is the closest to the geometric mean of the extreme frequencies of the subband.

For each NON TONAL components, the following has to be stored:

-	index k of the spectral lines which is the closed to the geometric
-	mean of the critical subband
-	SPL in dB of k-th line Xnm(k)
-	flag indicating NON-TONAL

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