Code validation

In this section we propose some elements of validation of the numerical code that are proposed in I-Simpa. When possible, numerical simulations are compared to other models or data from the scientific literature.

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.

Quasi-cubic room with specular reflection and uniform absorption

Description

Academic case: Quasi cubic room (8m x 10m x 9m) with specular reflection (no diffusion) and 10% uniform surface absorption, with a single source and 7 punctual receivers

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

What is tested?

Comparison between SPPS/TCR simulations and results from the NORMAL code described in [Yang, 2000].

[yang, 2000] L.N. YANG, B.M. SHIELD, DEVELOPMENT OF A RAY TRACING COMPUTER MODEL FOR THE PREDICTION OF THE SOUND FIELD IN LONG ENCLOSURES, Journal of Sound and Vibration, Volume 229, Issue 1, 2000, Pages 133-146, ISSN 0022-460X, dx.doi.org/10.1006/jsvi.1999.2477.

Cubic room with diffuse reflection and uniform absorption

Description

Academic case: Cubic room (10m x 10m x 10m) with 100% diffuse reflection and 20% uniform surface absorption, with a single source at (3,3,3) and 3 lines of 9 punctual receivers along the 3 diagionals of the room.

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 data from the radiosity method, as described in [Kang, 2002]. This allows to validate the diffuse reflection in SPPS.

[Kang, 2002] KANG, Jian. Acoustics of Long Spaces: theory and design guidance. Thomas Telford, 2002. www.thomastelford.com/books/bookshop_main.asp;

Long room with specular reflection and uniform absorption

Description

Academic case: Long room (8m x 100m x 9m) with specular reflection (no diffusion) and 10% uniform surface absorption, with a single source and 6 punctual receivers.

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/TCR simulations and results from the NORMAL code described in [Yang, 2000].

[yang, 2000] L.N. YANG, B.M. SHIELD, DEVELOPMENT OF A RAY TRACING COMPUTER MODEL FOR THE PREDICTION OF THE SOUND FIELD IN LONG ENCLOSURES, Journal of Sound and Vibration, Volume 229, Issue 1, 2000, Pages 133-146, ISSN 0022-460X, dx.doi.org/10.1006/jsvi.1999.2477.

Low room with mixed diffuse-specular reflection and non-uniform absorption

Description

Academic case: Low room (30m x 20m x 10m) with mixed reflection (varying scattering coefficient ) and non-uniform surface absorption, 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].

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.

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.

Low room with non-uniform absorption (comparison with experimental data)

Description

Low room (8m x 30m x 3.85m) with non-uniform absorption, with a single source, 7 receivers along a line and a reference 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 experimental data from [Ondet, 1989].

[Ondet, 1989] Ondet, A. M. , and Barbry, J. L. (1989). “ Modeling of sound propagation in fitted workshop using ray tracing,” J. Acoust. Soc. Am. 85(2 ), 787–796. doi.org/10.1121/1.397551

Industrial hall with non-uniform absorption and fitting objects (comparison with experimental data)

Description

Industrial hall (8m x 30m x 3.85m) with non-uniform absorption, with a single source, 7 receivers along a line and a reference receiver. This simulation includes 3 configurations (B, C and D) with different size for the fitting zone (entire hall, left part, right part), each with specific fittings properties (mean free path and absorption).

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 experimental data from [Ondet, 1989].

[Ondet, 1989] Ondet, A. M. , and Barbry, J. L. (1989). “ Modeling of sound propagation in fitted workshop using ray tracing,” J. Acoust. Soc. Am. 85(2 ), 787–796. doi.org/10.1121/1.397551

Large industrial hall with non-uniform absorption, 3 fitting zones and 30 workplace (i.e. 30 receivers)

Description

Very large industrial hall (107m x 42m x 5m) with non-uniform absorption, multiple sound sources (5 configurations: 1 (C1), 12 (C2), 22 (C3), 7 (C4) and 30 (C5) sound sources), 30 receivers. This simulation includes 3 fitting zones, with the same diffusion properties.

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 experimental data from [Ondet, 1988]. Additional information concerning the experimentation are given in [Ondet, 1984].

[Ondet, 1988] A.M. Ondet, J.L. Barbry, Sound propagation in fitted rooms—comparison of different models, Journal of Sound and Vibration, Volume 125, Issue 1, 1988, Pages 137-149, ISSN 0022-460X, http://dx.doi.org/10.1016/0022-460X

[Ondet, 1984] A.M. Ondet, J.L. Barbry, Prediction of noise levels in fitted rooms. Note Scientifique et Technique No. 52, INRS October 1984 (1984) (in French)

Two coupled cubic rooms with or without a door in a separation wall

Description

Academic case: Comparison between SPPS and the classical theory of coupled rooms, for 2 cubic rooms (5m x 5m x 5m) [10% absorption, 100% diffusely reflecting] with or without a 1.8m² door (open, closed (no transmission) or R=10 dB) in a separation wall with an insertion loss R=10, 20, 30 dB

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 theoretical results from the classical theory of reverberation applied to coupled rooms.