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US standards: Acoustic Index now shows NRC, SAA and inches

Next to the language you can now choose the standards. The ASTM edition shows NRC and SAA per ASTM C423 instead of αw and absorber class, with all dimensions in inches, in every language.

The page header has a second switch. The first picks the language, the second the standards: “ISO / EN” shows αw and the absorber class per ISO 11654 as before, “ASTM (US)” shows the same products with the ratings used in North America.

The standards switch in the page header with the options ISO / EN and ASTM (US)
Language and standards are two separate switches.

In the ASTM edition, result cards, filters, sorting, comparison, export and product pages carry the noise reduction coefficient (NRC) and the sound absorption average (SAA). Test methods lead with the US standard, ASTM C423 for the reverberation chamber and ASTM E1050 for the impedance tube. Thicknesses, air gaps and mounting depths are given in inches, plainly rounded, and room volumes in cubic feet.

Measurement data on a product page in the ASTM edition: thicknesses in inches with NRC ranges, the absorption curve below and NRC 0.85
A product page in the ASTM edition: thicknesses in inches, an NRC range for each.

The ratings are not estimates; they are computed from the lab curves. NRC is the mean of the absorption coefficients at 250, 500, 1,000 and 2,000 Hz, rounded to the nearest 0.05, and SAA the mean of twelve one-third-octave bands from 200 to 2,500 Hz. Where the curve comes from an ISO 354 measurement, the value is marked as derived.

Variant table in the ASTM edition with air gaps in inches, NRC per variant and the note that NRC is derived from ISO 354 lab data
NRC for every variant, with its origin noted next to the test report.

Visitors from the US or Canada start in the ASTM edition of their language automatically. Everyone else switches in the header, and the choice is remembered. The reverberation calculator also includes ANSI/ASA S12.60 for classrooms and LEED v4.

No account needed.

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