MEASURING THE VERTICAL DIRECTIONAL SPECTRA CAUSED BY SEA-SURFACE SOUND

This article discusses the results of the initial deployment of a wideband (40 to 4000 Hz) vertical acoustic antenna system in The Tongue of the Ocean (TOTO), The Bahamas. The instrumentation system consisted of seven octavely nested four-wavelength linear apertures covering the above frequency range, and a VCR-based subsurface recording system that carried out a programmed sequence of recordings. The objective of the measurement system is the development of a data base of directional spectra obtained in an acoustically isolated area where the ambient is principally controlled by the local (observable) sea surface conditions. The purpose of the data base is the identification of a model of the space-time statistics of the acoustic ambient caused by sea surface sound. Despite the limited acoustic aperture of the sensor system, quite adequate spatial resolution of the directional spectral estimates were obtained using a physically based parametric model of the random process. While there were aspects of the data unique to the location, the bulk of the information applies to the more-generic problem of characterizing the directional spectra resulting from a sea surface sound-source structure. © 1990 IEEE