### ASA 125th Meeting Ottawa 1993 May

## 2pUW2. Three-dimensional ocean acoustic propagation: Beyond the wedge.

**Grant B. Deane
**

**
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*Marine Phys. Lab. 0238, Scripps Inst. of Oceanography, 9500 Gilman Dr., La
Jolla, CA 92093-0238
*

*
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In recent years there has been an increasing interest in developing
analytical solutions to various range-dependent, three-dimensional propagation
problems. Calculation of the sound field from a point source in a homogeneous
wedge is such a problem. However, although interesting, the wedge is not
representative of the geometry of many shallow water channels. Over continental
shelf and slope regions, the bottom is often faceted, that is to say, the
channel can be represented as a ``hybrid duct'' constructed from two or more
planar boundaries. The wedge (two planes) and a parallel-sided duct terminated
by a wedge (three planes) are examples of hybrid ducts. A technique has been
developed for evaluating the field in a hybrid duct with perfectly reflecting
boundaries. The new method is based on a novel extension of the method of
source images, in which the concept of an image is abstracted into a set of
generating sequences and a visibility criterion. A solution will be presented
for the sound field in a duct terminated by a wedge as an example of this
technique. The method is exact provided the diffracted component of the sound
field is negligible. A description of how the source-image approach can be
extended to hybrid ducts with penetrable boundaries will be given.