Bijlage 2 Overzicht genormaliseerde octaafbanden en 1/3 octaafbanden

The table may be extended in either direction by successive multiplication or division by 1000. The letter x indicates in each column the geometric midband frequenties of the filter.

Preferred frequenties	1/1 octave	1/2 octave	1/3 octave	Preferred frequenties	1/1 octave	1/2 octave	1/3 octave	Preferred frequenties	1/1 octave	1/2 octave	1/3 octave
16	X	X	X	160			X	1600			X
18				180		X		1800
20			X	200			X	2000	X	X	X
22.4		X		224				2240
25			X	250	X	X	X	2500			X
28				280				2800		X
31.5	X	X	X	315			X	3150			X
35.5				355		X		3550
40			X	400			X	4000	X	X	X
45		X		450				4500
50			X	500	X	X	X	5000			X
56				550				5500		X
63	X	X	X	630			X	6300			X
71				710		X		7100
80			X	800			X	8000	X	X	X
90		X		900				9000
100			X	1000	X	X	X	10000			X
112				1120				11200		X
125	X	X	X	1250			X	12500			X
140				1400		X		14000
160			X	1600			X	16000	X		X

Note:

The exact preferred frequenties calculated from 1000 x 10^3n/10 for octave band filters, 1000 x 10^3n/10 for halve-octave band filters and 1000 x 10^n/10 for the third-octave band filters where n is a positive or negative integer, or zero, should be used for the design of filters rather than the nominal values given in the table.
For normal acoustical measurements, the difference between the nominal and the exact frequenties is negligible.

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Bijlage 2 Overzicht genormaliseerde octaafbanden en 1/3 octaafbanden