Modeling a representative room to evaluate sound power measurement methods for ASTM ISR testing

Abstract

ASTM ISR (Impact Sound Rating) test method suffers from non-reproducibility problems, especially in lower frequency bands in smaller rooms where the sound field is non-diffuse. The problem arises from the fact that Sound Pressure Level is measured in these rooms, which is dependent on the room dimensions if the sound field is non-diffuse due to low modal density. Currently, this non-diffusivity is ignored. We propose to measure sound power radiated from the ceiling instead of volume-averaged sound pressure level, which is independent of room dimensions regardless of the type of sound field in the receiving room. This study evaluates sixteen different ideas to measure sound power levels in the receiving rooms through a simulation model of a representative room using Simcenter 3D. Each method's pros and cons in the simulation are used to downselect methods to test in the field.