Interpretation of frequency-dependent transmission-loss interference patterns

Experimental observations of broad-band acoustic propagation in a known geological region of the Atlantic Generating Station (AGS) site (1994) has prompted a new approach to understanding frequency-dependent behavior in shallow-water regions. A modal-based theory is presented to explain quantitatively the interference patterns of transmission loss versus frequency observed in the experimental data. It is shown that the higher modes are responsible for observed interference patterns and that these can be related to modal group velocities using an ideal waveguide model. This may provide new insights applicable to existing inverse techniques.