Improved Room Acoustics Calculations Using Complex Impedance and Spherical Wave Reflection & Diffraction Coefficients (original) (raw)

Until recently geometrical acoustics has been considered an approximate method of calculating the sound field within a 3D environment because of certain limitations in existing methods. Geometrical acoustics mostly refers to the use of ray tracing and image sources. Ray tracing is a pure energetic method, while the image source method, despite calculating complex sound pressures and theoretically representing a solution to the wave equation, has certain limitations. One of the limitations found in most of the image source implementations is the use of plane wave reflection coefficient and absorption coefficients, a fact that prohibited image sources to be an exact solution of the wave equation. In this paper we extend the image source method, using spherical wave reflection and diffraction coefficients as well as complex surface impedance. We compare the results of the calculations with published data and we conclude that the use of spherical wave coefficients and complex impedance can improve room acoustics predictions.

Room Resonances Using Wave Based Geometrical Acoustics

Geometrical acoustics, using plane wave propagation and sound absorption coefficients, fail to calculate room resonances. Usually such wave phenomena are being calculated with numerical methods such as Finite Element Method or similar which are computationally heavy. The WBGA, which is based on the image source method, spherical wave propagation, impedance discontinu-ities and sound pressure summation, can accurately simulate room resonances both in the frequency and spatial domain. In this paper we present calculation results of room resonances using the WBGA compared to published data.

ROOM RESONANCES USING WAVE BASED GEOMETRICAL ACOUSTICS (WBGA

Geometrical acoustics, using plane wave propagation and sound absorption coefficients, fail to calculate room resonances. Usually such wave phenomena are being calculated with numerical methods such as Finite Element Method or similar which are computationally heavy. The WBGA, which is based on the image source method, spherical wave propagation, impedance discontinu-ities and sound pressure summation, can accurately simulate room resonances both in the frequency and spatial domain. In this paper we present calculation results of room resonances using the WBGA compared to published data.

Modelling Large Sound Sources in a Room Acoustical Calculation Program

A room acoustical model capable of modelling point, line and surface sources is presented. Line and surface sources are modelled using a special ray-tracing algorithm detecting the radiation pattern of the surfaces in the room. Point sources are modelled using a hybrid calculation method combining this ray-tracing method with Image source modelling. With these three source types, it is possible to model large and complex sound sources in workrooms.

The room acoustic rendering equation

2007

An integral equation generalizing a variety of known geometrical room acoustics modeling algorithms is presented. The formulation of the room acoustic rendering equation is adopted from computer graphics. Based on the room acoustic rendering equation, an acoustic radiance transfer method, which can handle both diffuse and nondiffuse reflections, is derived. In a case study, the method is used to predict several acoustic parameters of a room model.

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