WoodHighly absorbent

Physikalisch-Technische Bundesanstalt

Source: H. Lenz, Marktübersicht schallabsorbierende Anordnungen, Ruhr Universität Bochum, 1981, Seite 88

Value from the PTB table, not verified

Heraklith Herakustik HAK F wood wool fiber absorber

Herakustik, HAK F

PTB reference data

Original description

Material properties

Manufacturer: Deutsche Heraklith GmbH

Thickness: 25 mm, 35 mm

Wall distance: 250 mm, 25 mm, 30 mm, 0 mm, 290 mm, 50 mm

ISO 354 – reverberation chamber· 7 variants

α_w

0.90

α_p per ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.45	0.75	0.85	0.90	0.90	0.90

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			Value
25 mm	12 kg / m²	250 mm with 45 mm Mineralwollhinterfütterung	α_w0.90
35 mm	15,5 kg / m²	290 mm with 40 mm Mineralwollhinterfütterung	α_w0.90
25 mm	12 kg / m²	25 mm with 25 mm Mineralwollhinterfütterung	α_w0.60
35 mm	15,5 kg / m²	50 mm	α_w0.55
25 mm	12 kg / m²	30 mm	α_w0.40
35 mm	15,5 kg / m²	0	α_w0.35
25 mm	12 kg / m²	0	α_w0.30

Dimensions: 2000, 1000, 500 mm x 500 mm

Measured values as a table (7 measurements)

Heraklith Herakustik HAK F wood wool fiber absorber: 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
25 mm · 12 kg / m² · 250 mm with 45 mm Mineralwollhinterfütterung	0.90	0.20	0.48	0.60	0.65	0.76	0.86	0.84	0.85	0.93	0.90	0.90	0.93	0.92	0.92	0.92	0.86	0.85	0.98
25 mm · 12 kg / m² · 25 mm with 25 mm Mineralwollhinterfütterung	0.60	0.08	0.11	0.15	0.20	0.43	0.55	0.80	0.98	1.02	0.90	0.76	0.67	0.58	0.51	0.50	0.56	0.80	0.87
25 mm · 12 kg / m² · 30 mm	0.40	0.03	0.05	0.07	0.10	0.16	0.18	0.25	0.38	0.50	0.65	0.71	0.68	0.62	0.61	0.64	0.80	1.00	1.20
25 mm · 12 kg / m² · 0	0.30	0.03	0.04	0.05	0.08	0.13	0.12	0.20	0.23	0.26	0.35	0.47	0.63	0.82	0.86	0.80	0.62	0.61	0.73
35 mm · 15,5 kg / m² · 290 mm with 40 mm Mineralwollhinterfütterung	0.90	0.23	0.40	0.70	0.75	0.78	0.86	0.88	0.98	1.08	0.98	0.93	0.82	0.80	0.82	0.87	1.01	1.00	1.00
35 mm · 15,5 kg / m² · 50 mm	0.55	0.05	0.08	0.12	0.13	0.24	0.32	0.50	0.65	0.66	0.62	0.55	0.45	0.46	0.56	0.75	0.88	0.85	0.88
35 mm · 15,5 kg / m² · 0	0.35	0.05	0.05	0.07	0.06	0.13	0.13	0.24	0.27	0.40	0.55	0.78	0.84	0.80	0.66	0.61	0.63	0.87	1.00

Measured values as a table (7 measurements)

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Last updated: 16/09/2026