ASA 125th Meeting Ottawa 1993 May

3pAA4. Inter-laboratory comparisons of low-frequency sound transmission: II. Narrow-band measurements and computer simulations.

A. C. C. Warnock

IRC, Natl. Res. Council, M27 Montreal Rd., Ottawa, ON K1A 0R6, Canada

M. Vorlander

Phys. Tech. Bundesanstalt, W-3300 Braunschweig, Germany

Sound transmission through nominally identical 1.5x1.25-m steel plates was measured in two laboratories; NRC, Canada and PTB, Braunschweig in Germany. This sound paper presents results from a more detailed examination of the behavior of the sound fields at low frequencies in the laboratories. The long-term aim of the work is to understand reasons for poor reproducibility of low-frequency sound reduction measurements in laboratories. Narrow-band sound transmission measurements were made between the two pairs of rooms at PTB and NRC. In each case, the same procedure was used; loudspeakers were fed with a pseudorandom sequence and the impulse response was calculated using a Hadamard transform. The two sound transmission suites were also simulated using FEM and BEM programs. Comparisons between the measured and calculated results will be presented and discussed.