Conference_programme: 18.8 - Recent trends in numerical modeling: protocols and reliability
Lecture: Simulation of multiple Sound Particle Diffraction based on the Uncertainty Relation - a revolution in noise immission prognosis; Part II: Evaluation by Measurements
Author(s): Weigand Stefan, Stephenson Uwe, Schaal Jochen
Summary:
Since the early 1980s, the Sound Particle Simulation Method (SPSM) has been used in concert hall acoustics - but is naturally restricted to geometrical acoustics. Since 2006, the SPSM has been combined with Uncertainty Based Diffraction (UBD), to account for diffraction, e.g. in working rooms with screens. In this method, sound particles are deflected more strongly as they pass closer to edges. The distances are measured in wavelengths on virtual walls ("apertures"), introduced by a convex subdivision of the entire space. \nGiven a geometric model with known absorption and scattering coefficients, it now allows to calculate acoustic parameters like sound levels and reverberation times, including multiple diffractions in combination with specular and diffuse reflections.\nWhile studies comparing SPSM with UBDM with other numerical methods in 2D and 3D have already been performed and published, yet, no validation by direct comparison to measurements exists. To close this gap, we compare 3D simulations with full-scale measurements conducted in a hemi-anechoic chamber here. In combination with the use of absorptive foam mounted on the floor and surfaces, this allows us to examine diffraction in isolation, as well as in combination with floor and wall reflections. \nWe present results for various numbers and arrangements of screens. Different widths, heights and combinations of screens and reflectors are examined. The experiments are categorized in one-screen, two-screen and more complex screen scenarios. Impulse responses (IRs) are measured for several receiver and source positions. These IRs are then used to compute the insertion loss (IL) in octave bands. These ILs are compared to simulation results. \nThe results show an average difference below 1 dB and maximum of 5 dB, proving SPSM with UBD capable to successfully simulate multiple diffraction in combination with reflections. \nThe method is now being successfully used in the commercial software SoundPLANnoise.
Corresponding author
Name: Mr Stefan Weigand
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Country: Germany
