Part of the solution for sound field due to a point source in air over porous boundary has form an airborne surface wave. Analytical expressions wave characteristics are reviewed and corresponding analytical group speed obtained from thin layer approximation impedance comb-like surface, two approximate models acoustical properties media model identical slanted slit pores. Predictions absorption...

In the aim to find simplest and most efficient shape of a noise absorbing wall dissipate acoustical energy sound wave, we consider frequency model described by Helmholtz equation with damping on boundary. The well-posedness is shown in class domains $d$-set boundaries ($N-1\le d<N$). We introduce admissible Lipschitz boundaries, which an optimal exists following sense: prove existence Radon mea...

A new acoustical sensing system for the nuclear power industry has been developed at The Pennsylvania State University in collaboration with Idaho National Laboratories. This sensor uses the high temperatures of nuclear fuel to convert a nuclear fuel rod into a standing-wave thermoacoustic engine. When a standing wave is generated, the sound wave within the fuel rod will be propagated, by acous...

Modeling the acoustical process of soft biological tissue imaging and understanding the consequences of the approximations required by such modeling are key steps for accurately simulating ultrasonic scanning as well as estimating the scattering coefficient of the imaged matter. In this document, a linear solution to the inhomogeneous ultrasonic wave equation is proposed. The classical assumpti...

Sounds from a U.S. Navy SSQ-110A source are received at high signal-to-noise ratios at ocean-basin scales at two Sound Surveillance Systems in the Pacific. The sounds have sufficient pulse resolution to study climatic variations of temperature. The acoustic data can be understood using ray and parabolic approximations to the wave equation. Modeled internal waves decrease pulse resolution from 0...

on Γ := {(x1, 0) : x1 ∈ R}, where k > 0 (the wavenumber) is some arbitrary positive constant. This boundary value problem can arise when modelling the acoustic scattering of an incident wave by a planar surface with spatially varying acoustical properties [1]. The total acoustic field u ∈ C(U)∩C(U) satisfies (1)– (2) where the wavenumber k = 2πμ/c, with μ being the frequency of the incident wav...

The exact knowledge of the sound field within an enclosure is essential for a number of applications in electro-acoustics. Conventional methods for the assessment of room acoustics model the sound propagation in analogy to the propagation of light. More advanced computational methods rely on the numerical solution of the wave equation. A recently presented method is based on multidimensional wa...

In physics-based sound synthesis, it is generally possible to incorporate a mechanical or acoustical immittance (admittance or impedance) in the form of a digital filter. Examples include modeling of the termination of a string or a tube. However, when digital filters are fitted to measured immittance data, care has to be taken that the resulting filter corresponds to a passive mechanical or ac...

The application of the Functional Transformation Method (FTM) for the simulation of acoustical wave fields has been recently extended to complex room geometries by the usage of so called “block-based” modeling techniques. The complete model is split into several elementary blocks with simple geometry, which are solved separately with the FTM and reconnected in the discrete system with Wave Digi...