Application of sound to underwater acoustics

Experienced sonar operators can recognize various types of sounds. With the recent developement of time-domain underwater acoustics models and computer workstations capable of generating high-quality sounds from digital data, it is now possible to train the human ear to associate a wide variety of sounds with the underlying physics. With sufficient training, it might be possible to perform qualitative inversion problems such as estimating the range of a sound source, determining properties of the ocean sediment from a bottom-reflected signal, and recognizing the source of a scattered signal. Digitally generated sound can also be used in connection with time-domain signal-processing algorithms such as the delay-and-sum beamformer and the simulated annealing optimal beamformer [W. A. Kuperman et al., J. Acoust. Soc. Am. 88, 1802–1810 (1990)]. The synthesized sounds presented will include propagation to various ranges in different ocean environments, reflection from different types of ocean bottoms, scattering from bubble clouds near the ocean surface, and the application of beamforming to extract signals from interference (including a single speaker in a noisy crowd).