WoodHighly absorbent

Physikalisch-Technische Bundesanstalt

Source: H. Lenz, Marktübersicht schallabsorbierende Anordnungen, Ruhr Universität Bochum, 1981, Seite 152

Value from the PTB table, not verified

Wilhelmi Mikropor S acoustic panel with acoustic non-woven

Wilhelmi acoustic panel – Mikropor S (1981)

PTB reference data

Original description

Material properties

Manufacturer: Wilhelmi Werke AG

Thickness: approx. 18 mm

Wall distance: 50 mm, 300 mm

Backing: acoustic non-woven

Surface: fine-pored special lacquer

ISO 354 – reverberation chamber· 2 variants

α_w

0.60

α_p per ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.20	0.40	0.55	0.70	0.55	0.55

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Compare		Value
	50 mm	α_w0.60
	300 mm	α_w0.55

Weight / density: 6 - 7 kg / m²

Measured values as a table (2 measurements)

Wilhelmi Mikropor S acoustic panel with acoustic non-woven: 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	6300 Hz
ca. 18 mm · 6 - 7 kg / m² · 50 mm · acoustic fleece, feinporiger Speziallack	0.60	0.13	0.16	0.33	0.39	0.42	0.40	0.46	0.55	0.61	0.68	0.72	0.70	0.60	0.55	0.52	0.52	0.60	0.55	0.60
ca. 18 mm · 6 - 7 kg / m² · 300 mm · acoustic fleece, feinporiger Speziallack	0.55	0.45	0.42	0.33	0.25	0.28	0.32	0.39	0.49	0.66	0.70	0.78	0.72	0.66	0.58	0.55	0.55	0.62	0.55	0.56

Measured values as a table (2 measurements)

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Last updated: 02/09/2026