Low room with perfectly reflection and total ground absorption

Description

Academic case: Low room (30m x 20m x 10m) with perfeclty diffuse and reflecting surfaces, except the ground with a total, with a single source and 1 punctual receiver.

Licence Creative Commons
All elements of this simulation are licensed under a Creative Commons Attribution 4.0 International License.

What is tested?

Comparison between SPPS and the results obtained using a hybrid method (image-sources and radiosity) as described in [Korany, 2001], for a room with total ground absorption.

N. Korany, J. Blauert, O. Abdel Alim, Acoustic simulation of rooms with boundaries of partially specular reflectivity, Applied Acoustics, Volume 62, Issue 7, July 2001, Pages 875-887, ISSN 0003-682X, dx.doi.org/10.1016/S0003-682X(00)00075-X.

CAUTION - The following results present comparisons between numerical simulations carried out with I-Simpa and 'reference' data available in the scientific literature. However, it is difficult to prejudge the concept of 'reference'. The deviation between the simulations and the reference data that can be observed do not necessarily call into question the corresponding simulations but can also be associated with other sources of deviation (modeling assumptions, numerical instabilities, experimental uncertainties, etc.). In addition, some numerical models (like SPPS), based on random methods, may produce small deviations between two distinct simulations.

Results

Reverberation time (RT30)

The SPPS code gives a similar value of the reverberation time (RT30) than the hybrid method, while, as expected, the Sabine and Eyring formulae gives strong values for this specific room with a total absorption on the ground.

Calculation parameters

ParametersValue
Active calculation of Atmospheric absorptionNO
Active calculation of diffusion by fitting objectsNO
Active calculation of direct field onlyNO
Active calculation of transmissionNO
Calculation methodEnergetic
Limit value of the particle extinction5.0
Number of sound particles per source100 000 000
Number of sound particles per source (display)0
Random initialization number0
Receiver radius0.31
Simulation length (s)1.500
Time step (s)0.002