Computer simulations in room acoustics: Concepts and uncertainties

Abstract

Geometrical acoustics are used as a standard model for room acoustic design and consulting. Research on room acoustic simulation focuses on a more accurate modeling of propagation effects such as diffraction and other wave effects in rooms, and on scattering. Much progress was made in this field so that wave models also (for example, the boundary element method and the finite differences in time domain) can now be used for higher frequencies. The concepts and implementations of room simulation methods are briefly reviewed. After all, simulations in architectural acoustics are indeed powerful tools, but their reliability depends on the skills of the operator who has to create an adequate polygon model and has to choose the correct input data of boundary conditions such as absorption and scattering. Very little is known about the uncertainty of this input data. With the theory of error propagation of uncertainties it can be shown that prediction of reverberation times with accuracy better than the just noticeable difference requires input data in a quality which is not available from reverberation room measurements.

Uncertainty examination of ensemble averaging method for sound absorption of materials in a reverberation room

“…No distinct difficulty was found in measuring the reflective materials using EA method. Within the limited scope of this paper, all the uncertainty values were found to satisfy the requirement of ''less than 0.04'' [5]. Although the sample numbers and repetitions are not large, the authors infer that the fundamental applicability of EA method is confirmed including the measurements of reflective materials, and that the uncertainties of EA method remain with the range of expected values.…”

“…Based on several example calculations conducted for a music hall with volume of 11,000 m 3 , Vorländer pointed out that the uncertainty of the absorption coefficient must remain less than 0.04 to keep the uncertainty of calculated reverberation time below its just noticeable difference (JND) [5]. There followed the statement that such a small uncertainty cannot be obtained from the reverberation room method following ISO 354.…”

The relation between indoor environnemental quality (IEQ) and energy consumption in building based on occupant behavior - A review

“…In some studies IEQ aspects are considered based on temperature set points and ventilation rate [22] .There are different developed computational models for simulating each IEQ aspect [21,23,24]. Most of these simulating models consider each IEQ aspect separately and the inability to consider the interaction of a specific IEQ parameter with other IEQ Parameter is the drawback of these methods [25].Based on U.S Department of Energy (DOE2015) , just 2 of the 417 simulation software in the Building Energy, are capable to simulate all four IEQ aspects.…”

Measuring oblique incidence sound absorption using a local plane wave assumption

“…The availability of sound absorption data for oblique incidence would help in increasing the quality of room acoustic simulations, as shown by Vorländer [1]. However, such data is hardly available; typically one can only obtain the diffuse incidence sound absorption coefficient determined with the reverberation room method acc.…”