### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 5pUW3. An efficient broadband normal-mode model for acoustoelastic ocean
environments.

**Evan K. Westwood
**

**
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*Appl. Res. Labs., P.O. Box 8029, Univ. of Texas at Austin, Austin, TX
78713-8029
*

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A recently developed normal-mode model [E. K. Westwood et al., J. Acoust.
Soc. Am. 95, 2908(A) (1994)] for acoustoelastic ocean environments has been
extended to perform broadband calculations. The set of complex mode eigenvalues
at the highest frequency of interest is first found. Then each eigenvalue k[sub
n] is tracked as a function of frequency down to the lowest frequency of
interest. Analytic derivatives with respect to frequency dk[sub n]/d(omega) are
used to extrapolate in frequency, and step sizes are adjusted adaptively. When
the step size exceeds the FFT bin width, linear interpolation of eigenvalues
may be used. Examples of broadband calculations are given. [Work supported by
the ARL Internal Research and Development Program.]