GypsumBroadband absorber

Physikalisch-Technische Bundesanstalt

Source: H. Lenz, Marktübersicht schallabsorbierende Anordnungen, Ruhr Universität Bochum, 1981, Seite 195

Value from the PTB table, not verified

Knauf Perllit acoustic tile No. 74

Perllit acoustic tile – No. 74

PTB reference data

Original description

Material properties

Manufacturer: Knauf Hauptverwaltung Iphofen

Wall distance: 50 mm, 500 mm

Perforation: 5.8 %

Up to fire class: at least fire-retardant

Mounting: seamless installation

ISO 354 – reverberation chamber· 2 variants

α_w

0.35

α_p per ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.80	0.55	0.50	0.45	0.35	0.20

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Compare		Value
	500 mm	α_w0.35
	50 mm	α_w0.30

Weight / density: ca. 16 kg / m²

Dimensions: 625 x 625 mm

Measured values as a table (2 measurements)

Knauf Perllit acoustic tile No. 74: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	α_w	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
ca. 16 kg / m² · 50 mm	0.30	0.14	0.16	0.21	0.39	0.55	0.78	0.85	0.83	0.66	0.56	0.42	0.34	0.32	0.32	0.25	0.20	0.15	0.12
ca. 16 kg / m² · 500 mm	0.35	0.83	0.79	0.73	0.66	0.50	0.49	0.48	0.52	0.53	0.45	0.45	0.40	0.38	0.34	0.28	0.25	0.16	0.15

Measured values as a table (2 measurements)

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Last updated: 28/08/2026