Fraunhofer IBP micro-perforated metal cassette

PTB reference data

Original description

Material properties

Manufacturer: Fraunhofer IBP

Wall distance: 2 in, 3.9 in, 7.9 in, 16 in

Perforation: <1%

Hole size: 0 in

Application: suspended ceiling

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

NRC

0.50

α_p per octave band

f (Hz)	125	250	500	1k	2k	4k
α_p	0.35	0.60	0.65	0.40	0.35	0.15

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NRC: 0.50 (derived from ISO 354 lab data)

Measured values as a table (4 measurements)

Fraunhofer IBP micro-perforated metal cassette: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	NRC	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
50 mm	0.40	0.03	0.05	0.05	0.07	0.10	0.17	0.23	0.40	0.62	0.70	0.70	0.63	0.48	0.38	0.27	0.18	0.15	0.12
100 mm	0.45	0.06	0.07	0.12	0.22	0.28	0.46	0.61	0.67	0.71	0.67	0.55	0.41	0.34	0.30	0.27	0.18	0.18	0.09
200 mm	0.50	0.18	0.38	0.42	0.50	0.65	0.72	0.74	0.66	0.52	0.37	0.41	0.49	0.43	0.35	0.28	0.22	0.16	0.12
400 mm	0.50	0.33	0.61	0.76	0.70	0.68	0.60	0.44	0.39	0.50	0.45	0.47	0.46	0.46	0.37	0.32	0.23	0.15	0.12

Measured values as a table (4 measurements)

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Last updated: 08/28/2026