SOURCE LOCALIZATION IN UNDERWATER SOUND FIELDS

We investigated the acoustical information present in the field of arb itrary sound sources which may provide direction and distance to the s ource from a local reading of the sound field parameters. If the effec ts of reflections are negligible, the particle acceleration is directe d radially at the instant of sound pressure nulls. The spectral relati on between the radial component of the particle aceleration and the so und pressure is characterized by a critical frequency where a sharp tr ansition occurs in the amplitude ratio and the phase relation of these variables. The critical frequency depends on the distance to the sour ce and depends little on the source type (mono-, di- or quadrupole). T hus, a local reading of the particle acceleration and the sound pressu re is in principle sufficient to localize the sound source in three di mensions. Fish might use this kind of information for acoustic orienta tion.