FRIDAY MORNING, 20 MAY 2005 REGENCY E, 8:30 A.M. TO 12:00 ...

given the simple geometry, and serves to illustrate how a source can perturb
its field when near a boundary. Examples are presented for which
significant changes in the pressure magnitude occur. Work supported by
the Applied Research Laboratory, Penn State.
11:15
5aAA11. Subjective impression of differences in realism, source
width, and orientation between auralizations created from multichannel
anechoic recordings. Michelle C. Vigeant, Lily M. Wang
Architectural Eng. Prog., Univ. of Nebraska–Lincoln, Peter Kiewit Inst.,
1110 S. 67th St., Omaha, NE 68182-0681, mvigeant@unlnotes.unl.edu,
and Jens Holger Rindel Tech. Univ. of Denmark, DK-2800 Kgs. Lyngby,
Denmark
Auralizations can be very useful in the design of performing arts
spaces. One of the fundamental modeling inputs to create auralizations is
the source directivity. Standard methods involve inputting the measured
source directivity, calculating the impulse response IR and convolving it
with a single channel anechoic recording. This paper focuses on an alternative
method of modeling source directivity which involves multichannel
anechoic recordings to create auralizations. Subjective tests were
conducted comparing auralizations made with one, four and thirteen channels
for differences in realism and source width. Auralizations were made
using three different types of musical instruments: woodwinds flute,
brass trombone and strings violin. Subjects were asked to rate each
musical track on a seven-point scale for the degree of realism and source
width. An analysis of variance ANOVA was carried out to determine the
differences between the number of channels and the effect of instrument.
A second test was conducted to assess the degree of difficulty in detecting
source orientation facing the audience or facing the stage wall depending
on the number of channels one, four or thirteen and the amount of
absorption in the room. Work supported by the National Science Foundation.
11:30
5aAA12. Sampling methods for decay time evaluation in acoustically
coupled spaces. Tomislav Jasa, Ning Xiang, and Mendel Kleiner
School of Architecture and Dept. of Electrical, Computer, and Systems
Eng., Rensselaer Polytechnic Inst., Troy, NY 12180
This paper applies the methods of Bayesian inference to the estimation
of decay times in coupled rooms. Previous papers N. Xiang and P. M.
Goggans, J. Acoust. Soc. Am. 110, 1415–1424 2001; 113, 2685–2697
2003 developed a solution method to estimate the decay times and the
number of decay modes in terms of measured Schroeder’s decay functions.
This paper extends the previous work by using statistical sampling
methods to efficiently determine the decay times along with error estimates
and evaluate the ‘‘Bayesian evidence’’ term used in determining the
number of decay modes. This paper discusses the implemented methods
together with the previous work to solve the problem of decay time estimation
as well as determining the number of decay modes in acoustically
coupled rooms.
11:45
5aAA13. Experimental validation of a diffusion equation-based
modeling of the sound field in coupled rooms. Alexis Billon, Vincent
Valeau LEPTAB Univ. of La Rochelle, Av. M. Crepeau 17042, La
Rochelle Cedex 01, France, abillon@univ-lr.fr, Judicael Picaut LCPC
Nantes ESAR Rte. de Bouaye–BP 4129 44341, Bouguenais Cedex,
France, and Anas Sakout LEPTAB, La Rochelle, France
Sound modeling in coupled rooms i.e., two acoustically coupled
rooms separated by an open area has attracted considerable attention in
the past. However accurate and operational models are still needed, principally
when three or more rooms are coupled. In recent papers, a diffusion
equation-based model has been applied to unusual room shapes. For
the coupled rooms geometry, this diffusion model has been validated successfully
by comparison with the classical statistical theory in a parametrical
study of the coupling parameters Billon et al., J. Acoust. Soc. Am.
116, 2553 2004. In the present work, the diffusion model results are
validated by means of a comparison with experimental results, both in
terms of sound attenuation and reverberation time. A comparison is also
provided with results given by the statistical theory and a ray tracing
program. For this purpose, experiments have been conducted in two
coupled classrooms with two different sound source locations. The results
show a very good agreement between the diffusion model and the experiments.
Conversely, the statistical model is not valid for modeling accurately
the sound field distribution and decay in both coupled rooms. At
last, the diffusion model runs much faster than the ray tracing program.
5a FRI. AM
2581 J. Acoust. Soc. Am., Vol. 117, No. 4, Pt. 2, April 2005 149th Meeting: Acoustical Society of America 2581