• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Next Issue

Jan 2011

Volume 129, Issue 1, pp. EL1-547

Return to All Sections
back to top
RSS Feeds

Higher mode sound transmission from a point source through a rectangular aperture

J. L. Horner and K. S. Peat

J. Acoust. Soc. Am. Volume 129, Issue 1, pp. 5-11 (2011); (7 pages)

Online Publication Date: 02 Feb 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper considers the higher-order scattered and transmitted wave fields that result when an acoustic wave from a point source impinges at an arbitrary angle on a rectangular aperture in a rigid, thick wall. In this analysis, it is assumed that free field conditions exist on both sides of the aperture. Although the full scattered and transmitted pressure fields contain both modal sum and modal coupling effects, the modal coupling effects of the higher-order modes are ignored such that an approximate analytical solution to the uncoupled analysis can be utilized. Experiments have been undertaken to measure the sound pressure levels in the transmitted field that result when sound from a point source impinges on the opposite side of a rectangular aperture. Measurements were made with the source located at the required position to drive a particular in-aperture higher-order mode. The source was also located at positions that did not directly excite any in-aperture higher-order mode at a cut-on frequency. These results indicate that the approximate analysis developed here gives accurate solutions whether or not any mode of the aperture is driven at cut-on. Thus, the method can be used for any relative location of a source from a rectangular aperture of any dimensions.
Show PACS
43.20.Fn Scattering of acoustic waves

Acoustical scattering by multilayer spherical elastic scatterer containing electrorheological layer

Liang-Wu Cai, Dacio K. Dacol, Gregory J. Orris, David C. Calvo, and Michael Nicholas

J. Acoust. Soc. Am. Volume 129, Issue 1, pp. 12-23 (2011); (12 pages) | Cited 1 time

Online Publication Date: 02 Feb 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A computational procedure for analyzing acoustical scattering by multilayer concentric spherical scatterers having an arbitrary mixture of acoustic and elastic materials is proposed. The procedure is then used to analyze the scattering by a spherical scatterer consisting of a solid shell and a solid core encasing an electrorheological (ER) fluid layer, and the tunability in the scattering characteristics afforded by the ER layer is explored numerically. Tunable scatterers with two different ER fluids are analyzed. One, corn starch in peanut oil, shows that a significant increase in scattering cross-section is possible in moderate frequencies. Another, fine poly-methyl methacrylate (PMMA) beads in dodecane, shows only slight change in scattering cross-sections overall. But, when the shell is thin, a noticeable local resonance peak can appear near ka = 1, and this resonance can be turned on or off by the external electric field.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Gp Reflection, refraction, diffraction, interference, and scattering of elastic and poroelastic waves
43.35.Mr Acoustics of viscoelastic materials

Green’s function of radial inhomogeneous spheres excited by internal sources

Grigorios P. Zouros and Gerassimos C. Kokkorakis

J. Acoust. Soc. Am. Volume 129, Issue 1, pp. 24-31 (2011); (8 pages) | Cited 1 time

Online Publication Date: 02 Feb 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Green’s function in the interior of penetrable bodies with inhomogeneous compressibility by sources placed inside them is evaluated through a Schwinger–Lippmann volume integral equation. In the case of a radial inhomogeneous sphere, the radial part of the unknown Green’s function can be expanded in a double Dini’s series, which allows analytical evaluation of the involved cumbersome integrals. The simple case treated here can be extended to more difficult situations involving inhomogeneous density as well as to the corresponding electromagnetic or elastic problem. Finally, numerical results are given for various inhomogeneous compressibility distributions.
Show PACS
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Ks Standing waves, resonance, normal modes
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close