Energy- and wave-based beam-tracing prediction of room-acoustical parameters using different boundary conditions

Murray Hodgson , Behrooz Yousefzadeh

A beam-tracing model was used to predict the transient responses of rooms. The model is wave-based and can be applied to rooms with extended-reaction surfaces. Room surfaces can be modeled as multiple layers of solid, fluid or poro-elastic materials with acoustical properties that are calculated using Biot theory. Both wave-based and energy-based versions of the beam-tracing model have been applied to various room configurations to study the effects of using different boundary conditions (local vs. extended reaction and phase changes on reflection) on room-acoustical parameters. Very significant differences occurred in all parameters when interference effects were taken into account, whether partly (ignoring phase change on reflection) or entirely (wave-based modeling). Modeling surfaces as of local or of extended reaction was found to be significant for surfaces that consist of multiple layers, specifically when one of the layers is air. For multi-layers of solid materials with an air-cavity, significant differences occurred around their mass-air-mass resonance. While these changes affected reverberation times and sound strengths in most room configurations, their effect on Rapid Speech Transmission Index remained mostly insignificant. The results have been explained in part by considering the absorption and reflection characteristics of the test surfaces used in each configuration.

Mots clés: beam tracing prediction; room-acoustical parameters; boundary conditions; energy and wave based

Domaines: Acoustique [physics.class-ph]

Murray Hodgson, Behrooz Yousefzadeh. Energy- and wave-based beam-tracing prediction of room-acoustical parameters using different boundary conditions. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811330⟩