The energy flow for a spherical acoustic lens: experimental results avoiding interference effects

Document Type

Article

Publication Date

3-23-2010

Publication Title

Journal of the Acoustical Society of America

DOI

10.1121/1.3384845

ISSN

0001-4966

Abstract

A simple classroom demonstration consists of a weather balloon filled with carbon dioxide, a sound source, and a microphone. Since the speed of sound is slower in carbon dioxide than in air at room temperature and pressure, the balloon acts as a positive spherical acoustic lens. Preliminary experimental results have been presented previously [C. E. Dean and J. P. Braselton, “The energy flow for a spherical acoustic lens: ray and wave methods vs. experiment.,” J. Acoust. Soc. Am. 125, 2627 (2009)]. The possibility of interference effects from the reflection of sound off surfaces was brought up in the ensuing discussion. The current results have been measured in a way that minimizes the effect of interference due to reflections off walls, floor, or other surfaces.

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Copyright 2010 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.

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