Time-Domain Modeling of the Acoustic Impedance of Porous Surfaces
Abstract:A time-domain boundary condition (TDBC) for acoustic reflections from a rigid-frame porous material is derived. The TDBC is the time-domain counterpart of the familiar, linear, frequency-dependent surface impedance for locally reacting surfaces. Although the TDBC is developed from a rather simple, two-parameter phenomenological model, it is shown to apply to a broad range of frequencies and to agree closely with predictions from more sophisticated models that do not have readily derivable time-domain formulas. The TDBC gives the pressure as the sum of two terms involving the particle velocity normal to the surface of the material: one term is directly proportional to the particle velocity at the present time, whereas the other involves a convolution of the particle velocity with a slowly decaying response function. Numerical implementation of the TDBC is discussed and illustrated with example finite-difference, time-domain calculations involving propagation over a porous ground surface.
Document Type: Research Article
Publication date: November 1, 2006
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- Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.
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