CATT-Acoustic: Image source modelling augmented by ray tracing and diffuse reflections : Dalenbäck, B.-I. Department of Applied Acoustics, Chalmers University of Technology, S-41296 Gothenberg, Sweden.

Abstract

The purpose of this research is to investigate the accuracy provided by different algorithms for room acoustics simulation. Three software packages are used to simulate the monaural room impulse responses of a medium-sized concert hall. All algorithms deal with geometrical acoustics but with distinct implementations. The simulated room is one of those adopted as a benchmark for the first round robin on room acoustical simulation and auralization, the last international inter-comparison, for which the geometrical and acoustic data were carefully measured. The main novelty is the inclusion of the software RAIOS, which participated in the round robin but did not finish the simulations in time to be included in the publication. Four acoustical parameters, namely the reverberation time, the early decay time, the clarity factor for music, and the definition for speech, are computed for ten source-receiver pairs at octave band frequencies from 125 Hz to 8 kHz. The results obtained by the three software are then compared with the measured data for all source-receiver positions and frequency bands. The relative mean errors to the just noticeable difference (JND) are also computed. The main findings are that there are deviations relative to the measured results for all software, with some of the parameters being better evaluated than others are. Preliminary insights into the advantages and limitations of the software packages with respect to the monaural impulse response are also given.