Reference surfaceLow-frequency absorber
Data source
PTB reference data
Physikalisch-Technische Bundesanstalt
Source: Sound System Engineering, Don Davis and Carolyn Davis
Value from the PTB table, not verified
Roofing felt, bituminous, two layers, 0.8 lb/ft², mounted over 10 inch air space
PTB reference data
Original description
Roofing felt, bituminous, two layers, 0.8 lb/ft², mounted over 10 inch air space
Material properties
Wall distance: 10 inch
Surface weight: 0.8 lb/ft²
Measurement data
Sound absorption
ISO 354 – reverberation chamber
αw
0.15
Frequency values
αp nach ISO 11654
| f (Hz) | 125 | 250 | 500 | 1k | 2k | 4k |
|---|---|---|---|---|---|---|
| αp | 0.50 | 0.30 | 0.20 | 0.10 | 0.10 | 0.10 |
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Value from the PTB table, not verified
Measured values as a table (1 measurement)
| Build-up | αw | 125 Hz | 250 Hz | 500 Hz | 1000 Hz | 2000 Hz | 4000 Hz |
|---|---|---|---|---|---|---|---|
| 0,8 lb/ft² · 10-in | 0.15 | 0.50 | 0.30 | 0.20 | 0.10 | 0.10 | 0.10 |
Measured values as a table (1 measurement)
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