Acoustic panel with fine slotting / 20 cm air cavity

PTB reference data

Original description

Material properties

Wall distance: 7.9 in

Reverberation chamber (ASTM C423 / ISO 354)

NRC

0.80

derived from ISO 354 lab data

α_p nach ISO 11654

f (Hz)	125	250	500	1k	2k	4k
α_p	0.60	0.90	0.95	0.75	0.50	0.35

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Value from the PTB table, not verified

NRC: 0.80 (derived from ISO 354 lab data)

Measured values as a table (1 measurement)

Acoustic panel with fine slotting / 20 cm air cavity: sound absorption coefficient αs per ISO 354 by frequency and test build-up
Build-up	NRC	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz
20 cm	0.80	0.60	0.90	0.95	0.75	0.50	0.35

Measured values as a table (1 measurement)

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Last updated: 08/28/2026