Measurements of the horizontal directionality of the ambient acoustic noise in Monterey Bay, California

Abstract

Measurements of some of the horizontal characteristics of acoustic ambient noise were carried out in the south-eastern parts of Monterey Bay, California, at a limited number of stations and for a limited number of ambient conditions. Directional hydrophones on buoys located at ranges of two to four miles from shore were used which have a steerable, cardioid-shaped pattern. The beam was successively aimed along the four cardinal directions and the frequency spectrum of the output was obtained. The frequency range of the system response was from 10 to 2500 Hz. Results are presented in the form of differences between the spectral energy bins in each direction and the average over all directions. Experimental difficulties with sonobuoy reliability prevented collection of extensive data. Some tentative conclusions are drawn from the results.