The effect of ancillary volume on sound transmission measurements using ASTM standard test method E336

Frances King, Trevor R. T. Nightingale

Abstract


The effects of ancillary volume on sound transmission measurements by ASTM Standar E336-05 to access airborne sound isolation, are described. The ancillary volume is required to be disregarded if the average sound pressure level in the ancillary volume is more than 6. Different field scenarios are simulated using the four-room Flanking Transmission Facility at the NCR/IRC. The effect is considerably less when the ancillary volume is highly absorptive relative to the receive room principal volumes. The difference in the ALT with and without an ancillary volume is a function of two parameters. The first one is space-average level between the principal and ancillary volumes, and the second is sound field measurements associated with the ancillary volume. Estimates of the ALT is obtained using sound field measurements restricted to the principal volume when the difference in space average level between the principal and ancillary volume is more than 4 dB.

Keywords


Absorption; Acoustic variables measurement; Parameter estimation; Signal receivers; Sound field measurements; Sound pressure; Sound transmissions

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