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# Accession Number:

## AD0435480

# Title:

## ANALYTIC FORMULAS FOR THE ACOUSTIC PRESSURE DISTRIBUTION BETWEEN A SPHERICAL TRANSDUCER AND A CONCENTRIC SPHERICAL BAFFLE.

# Descriptive Note:

## Interim rept.,

# Corporate Author:

## NAVAL RESEARCH LAB WASHINGTON D C

# Report Date:

## 1964-01-17

# Pagination or Media Count:

##
9.0

# Abstract:

## A sphere having arbitrary distribution of normal velocity over its surface and surrounded partially by a spherical baffle board radiates sound into infinite space. In the region between the radiating sphere and the baffle board the resultant sound field consists of a set of incoming and outgoing waves described by an appropriate set of spherical wave functions. These functions are adjusted to yield a normal component of particle velocity distribution which matches the velocity distribution at the surface of the sphere. In the region outside the baffle the sound field corresponds to outgoing waves only. At the junction of the inner and outer regions over those portions of arc where no baffle exists the condition of continuity requires that pressures and particle velocities agree as the boundary is crossed. This requirement of continuity equates the infinite series of spherical wave functions in the outer region to an infinite series of different spherical wave functions in the inner region. The result is an infinite set of simultaneous equations in an infinite set of unknown expansion constants. Further treatment of these constants varies with the acoustic properties of the baffle. Baffles are considered which have surfaces of either zero pressure or zero normal components of particle velocity and the corresponding sets of equations are derived. A brief discussion is also made of the case where the baffle has an acoustic impedance which is neither zero nor infinite. Author

# Distribution Statement:

## APPROVED FOR PUBLIC RELEASE

#