Perforated metal cassette with mineral fiber backing, spacing 180 mm

PTB reference data

Original description

Material properties

Wall distance: 7.1 in

Dimensions: 625 × 25 in

Surface weight: 2 kg/m²

Perforation: 16%

Hole size: 0.1 in

Backing: 0.8 in mineral fiber panel

Surface: surface-treated

Reverberation chamber (ASTM C423 / ISO 354)

NRC

0.85

derived from ISO 354 lab data

α_p nach ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.25	0.65	0.95	0.85	0.85	0.80

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Value from the PTB table, not verified

NRC: 0.85 (derived from ISO 354 lab data)

Measured values as a table (1 measurement)

Perforated metal cassette with mineral fiber backing, spacing 180 mm: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	NRC	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
180 mm	0.85	0.17	0.35	0.48	0.71	0.83	0.90	0.95	0.93	0.90	0.79	0.80	0.83	0.87	0.83	0.85	0.77	0.80

Measured values as a table (1 measurement)

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Last updated: 09/02/2026