DAGA 2010 - Deutsche Gesellschaft für Akustik eV

220 DAGA 2010 Programm
Mi. 15:40 Bauwesen H2 Virtuelle Akustik I
Room Modelling for Acoustic Simulation and Auralization Tasks:
Resolution of Structural Details
S. Pelzer a und H.-J. Maempel b
a Institut für Technische Akustik, RWTH Aachen; b TU Berlin, Fachgebiet
Audiokommunikation
The CAD models that are required for room acoustic simulations or auralizations
based on geometrical methods have to fulfill several conditions -
one of them stating the assumption that all faces of walls and objects are
larger than any wavelength of interest. For audible sounds those wavelengths
range from 1.7cm to 17m, exceeding the dimensions of common
objects and room boundaries, so that a broadband simulation using only
one fix model can’t deliver correct results.
A new approach introduces a set of models of the same room but with
graduated level of detail. These different models can account for more
physical correctness especially for very low frequency specular reflections.
Furthermore they allow to speed up the simulation process, which
is important e.g. for real-time applications like virtual environments. The
speed-up is achieved by the reduced number of polygons especially for
low frequencies, where lower absorption usually causes higher reflection
orders.
In order to ascertain, how much simplification of the room geometry
is allowed without being audible, and without negatively affecting the
perceptual evaluation of naturalness respectively, ABX tests as well as
triple-stimulus tests with hidden reference have been performed by expert
listeners. Results of the comparison of highly detailed geometry,
simplified geometries, and frequency-dependent dimensions of structural
details will be presented.
Mi. 16:30 Bauwesen H2 Virtuelle Akustik I
Optimization of Input Parameters for the Real-time Simulation of
Room Acoustics - Revisited
D. Schröder a ,B.Starke a und H.-J. Maempel b
a Institut für Technische Akustik, RWTH Aachen; b TU Berlin, Fachgebiet
Audiokommunikation
Immersive environments mostly aim to simulate opto-acoustical scenes
in a plausible way. For real-time auralization, methods of geometrical
acoustics provide quite accurate results within a reasonable computation
time. The best results are achieved by combining deterministic methods
for the computation of early specular reflections with stochastic approaches
for the computation of the reverberant sound field. The computations
must be performed at interactive rates, thus their costs have to be
minimized. This is typically done by reducing the order of image sources
and/or the number of traced rays, as these parameters strongly influence
both, the computational costs and the perceptual accuracy of the
simulation. Since the degradation caused by the reduction has not to be