Articles tagged “astm c423”
3 articles covering astm c423 in acoustic engineering and building design.
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GUIDES8 min read
NRC vs αw vs SAA: Three Ways to Measure Absorption
Understand the differences between NRC, weighted sound absorption coefficient (αw), and SAA ratings with practical guidance on which metric to specify.
March 20, 2026
NRCαw
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STANDARDS12 min read
ASTM C423 Absorption Testing: Test Method, Mounting Types, and Why Results Vary
ASTM C423 is the US standard for measuring sound absorption coefficients in a reverberation room. This guide explains the test method, mounting types A–J, NRC calculation, and why the same product can yield very different results.
March 18, 2026
ASTM C423absorption testing
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GUIDES17 min readFeatured
NRC 0.75 Does Not Mean 75% Absorption — Here Is What It Actually Means
NRC is an arithmetic average of four octave bands. A panel rated NRC 0.75 can have α = 0.40 at 250Hz — and that bass deficiency will make your meeting room fail its WELL F74 assessment at the exact frequency where speech intelligibility lives.
March 13, 2026
NRCabsorption coefficient