The Effect of Active Sonar on Human Hearing pp. 239-247
Authors: (Luca Guastini, Renzo Mora, Santomauro Valentina, Barbara Crippa, ENT Department, University of Genoa, Italy)
Abstract: Sonar (for sound navigation and ranging) is a technique that uses sound propagation (usually underwater) to navigate, communicate or to localize: sonar may be used as a means of acoustic location (acoustic location in air was used before the introduction of radar). The term sonar is also used for the equipment used to generate and receive the sound. The range of frequencies used in sonar systems vary from infrasonic to ultrasonic. Sonar propagation is related to variations in sound speed, particularly in the vertical plane. Although the difference in speeds between fresh and salt water is small, sound travels more slowly in fresh water than in sea water; in all water the sound speed is determined by its bulk modulus and mass density. While the density effect is small, the bulk modulus is affected by temperature, dissolved impurities, and pressure.