Sheet Metal Round, Glass Wool 90 mm R2.7, No MLV

Round perforations only, hole diameter varied.

Tests

2

Effect of Hole Diameter

Rw range

17dB

spread 0 dB

Highest Rw

17dB

SM 1.6 mm Round (11.0%)

Largest ΔRw vs first

±0dB

SM 2.38 mm Round (23.0%)

Sound reduction index

R′ from the 2270, re-referenced to the 0.9216 m² specimen area (−0.35 dB). Grey lines: reference bounds.

Single-number ratings

Open in explorer
VariesTestRwCCtrΔRw vs firstΔRw vs openMean R
SM 1.6 mm Round (11.0%)Project042
17
0−3ref.+1716.5
SM 2.38 mm Round (23.0%)Project046
17
0−3±0+1716.4

Rw, C and Ctr per ISO 717-1 over 100–3150 Hz. ΔRw fits the reference curve to the band-by-band difference curve, which is not the same number as subtracting two separately rounded Rw values. Mean R is the arithmetic mean over the 16 rating bands.