Let M be the number of bounded and Lipschitz regular obstacles Dj , j := 1, ...,M having a maximum radius a, a << 1, located in a bounded domain Ω of R. We are concerned with the acoustic scattering problem with a very large number of obstacles, as M := M(a) := O(a−1), a → 0, when they are arbitrarily distributed in Ω with a minimum distance between them of the order d := d(a) := O(a) with t in...

We consider the numerical solution of the wave equation with impedance boundary conditions and start from a boundary integral formulation for its discretization. We develop the generalized convolution quadrature (gCQ) to solve the arising acoustic retarded potential integral equation for this impedance problem. For the special case of scattering from a spherical object, we derive representation...

The structural changes in a magnetic fluid (formation of clusters) upon the effect of an external magnetic field were studied by acoustic spectroscopy. The properties of magnetic fluid dispersed in inhibited transformer oil ITO 100 have been studied by the analysis of changes in the acoustic wave absorption coefficient. The absorption coefficient of acoustic waves was measured as a function of ...

Over the past several decades, many acoustic markers have been proposed to be sensitive to and measure overall voice quality. This meta-analysis presents a retrospective appraisal of scientific reports, which evaluated the relation between perceived overall voice quality and several acoustic-phonetic correlates. Twenty-five studies met the inclusion criteria and were evaluated using meta-analyt...

The interaction of an acoustic wave with two joined flat plates results in a diffracted acoustic wave emanating from the junction. The plates are assumed, for simplicity, to have different masses but no stiffness, and the exact solution of the two-dimensional diffraction problem is derived as a Fourier integral. The diffraction coefficient for a plane acoustic wave is found to depend in a simpl...

In this paper we address a series of so-called local plane wave methods (LPW) to measure acoustic absorption. As opposed to other methods, these methods do not rely on assumptions of the global sound field, like e.g. a plane wave or diffuse field, but are based on a local plane wave assumption. Therefore, the LPW methods can be used for any given surface/absorbing material and any arbitrary sou...

Using a local plane wave assumption, one can determine the normal incidence sound absorption coefficient of a surface by measuring the acoustic pressure and the particle velocity normal to that surface. As the measurement surface lies in front of the material surface, the measured active and incident acoustic power will generally deviate from those at the material surface, leading to a possibly...