WoodHighly absorbent

Physikalisch-Technische Bundesanstalt

Source: Manufacturer data im Internet, mit Verweis auf ita-Prüfzeugnis, 14.11.2000

Value from the PTB table, not verified

Wilhelmi Variante X wood acoustic panel (series 3)

Variante X

PTB reference data

Original description

Material properties

Manufacturer: Wilhelmi Werke AG

Wall distance: 7.9 in

Surface: decorative fine chip top layer, natural or Wilhelmi acoustic color coating

Reverberation chamber (ASTM C423 / ISO 354)

NRC

0.65

derived from ISO 354 lab data

α_p nach ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.40	0.50	0.55	0.60	0.70	0.60

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Value from the PTB table, not verified

NRC: 0.65 (derived from ISO 354 lab data)

Measured values as a table (1 measurement)

Wilhelmi Variante X wood acoustic panel (series 3): 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
Measurement 1	0.65	0.48	0.42	0.35	0.42	0.59	0.55	0.57	0.56	0.53	0.51	0.65	0.71	0.71	0.72	0.65	0.63	0.60	0.62

Measured values as a table (1 measurement)

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Last updated: 09/04/2026