Glass & transparentBroadband absorber

Physikalisch-Technische Bundesanstalt

Source: IBP Mitteilung 258, Fraunhofer-Inst. F. Bauphysik, Stuttgart, 1994

Value from the PTB table, not verified

Micro-perforated acrylic glass sound absorber

PTB reference data

Original description

Material properties

Thickness: 0.2 in

Wall distance: 3.9 in, 1 in, 2 in

Reverberation chamber (ASTM C423 / ISO 354)· 4 variants

NRC

0.55

α_p per octave band

f (Hz)	125	250	500	1k	2k	4k
α_p	0.25	0.60	0.85	0.50	0.25	0.15

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		Value
3.9 in	Lochdurchmesser 0 in, Lochabstand 0.1 in	NRC0.55
1 in	Lochdurchmesser 0 in, Lochabstand 0.2 in, Lochflächenanteil 0,0314 %	NRC0.35
2 in	Lochdurchmesser 0 in, Lochabstand 0.1 in, Lochflächenanteil 0,0207%	NRC0.35
3.9 in	Lochdurchmesser 0 in, Lochabstand 0.2 in, Lochflächenanteil 0,0140 %	NRC0.35

NRC: 0.55 (derived from ISO 354 lab data)

Measured values as a table (4 measurements)

Micro-perforated acrylic glass sound absorber: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	NRC	63 Hz	80 Hz	100 Hz	125 Hz	160 Hz	200 Hz	250 Hz	315 Hz	400 Hz	500 Hz	630 Hz	800 Hz	1000 Hz	1250 Hz	1600 Hz	2000 Hz	2500 Hz	3150 Hz	4000 Hz	5000 Hz
5 mm · 100 mm · Lochdurchmesser 0,55 mm, Lochabstand 3,5 mm	0.55	0.13	0.12	0.12	0.25	0.35	0.40	0.50	0.93	0.91	0.93	0.70	0.60	0.45	0.39	0.28	0.25	0.22	0.18	0.22	0.08
5 mm · 25 mm · Lochdurchmesser 0,65 mm, Lochabstand 4 mm, Lochflächenanteil 0,0314 %	0.35	0.00	0.00	0.00	0.00	0.00	0.02	0.09	0.12	0.25	0.50	0.85	0.93	0.65	0.37	0.20	0.18	0.15	0.08	0.05	0.05
5 mm · 50 mm · Lochdurchmesser 0,55 mm, Lochabstand 3,5 mm, Lochflächenanteil 0,0207%	0.35	0.00	0.00	0.02	0.05	0.10	0.20	0.35	0.60	0.98	0.85	0.70	0.30	0.20	0.15	0.10	0.08	0.05	0.02	0.00	0.00
5 mm · 100 mm · Lochdurchmesser 0,8 mm, Lochabstand 6 mm, Lochflächenanteil 0,0140 %	0.35	0.05	0.08	0.20	0.30	0.45	0.85	0.98	0.80	0.40	0.30	0.20	0.15	0.10	0.08	0.02	0.05	0.20	0.02	0.00	0.00

Measured values as a table (4 measurements)

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Last updated: 09/07/2026