back ceiling TI-Metal holes 2mm + L.M. 30mm

PTB reference data

Original description

Material properties

Hole size: 0.1 in

Backing: 1.2 in mineral wool

Reverberation chamber (ASTM C423 / ISO 354)

NRC

0.90

derived from ISO 354 lab data

α_p nach ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.25	0.70	0.95	0.90	0.95	0.85

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Value from the PTB table, not verified

NRC: 0.90 (derived from ISO 354 lab data)

Measured values as a table (1 measurement)

back ceiling TI-Metal holes 2mm + L.M. 30mm: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	NRC	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz
Measurement 1	0.90	0.15	0.24	0.70	0.97	0.90	0.95	0.85	0.80

Measured values as a table (1 measurement)

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Last updated: 08/28/2026