"Sonar target-identification by means of an acoustic spectroscopy scheme"

An acoustic target may be characterized by the frequency spectrum of its eigenvibrations as to size, shape and composition. Resonance effects corresponding to acoustic excitation of the eigenvibrations, which are contained in the backscattered echoes, can be used for target-identification purposes. We here study the dependence of the resonance spectra of fluid targets in vacuo on target shape, in order to illustrate this approach, presenting the eigenfrequency spectra in the form of "level schemes" as in atomic spectroscopy, and hereby introducing the concept of "acoustic spectroscopy".