Do dolphins alter their vocal behavior in response to military sonar? A review of analytical methods

About

The vocal repertoire of dolphins encompasses three categories of vocalisations - whistles, clicks and buzzes -which are used in different contexts, e.g. for socialising, under water echolocation or homing in on prey during foraging. Mid-frequency active sonar (MFAS) is used by military vessels for detecting objects. It involves the underwater emission of intense sound pulses that are often repeated. As the range of sound frequencies used for MFAS often overlaps that of dolphin vocalisations, we were interested in identifying any potential changes in the vocal behaviour that dolphins may exhibit in response to military sonar exercises. To identify such changes, we compare the vocal behaviour of dolphins from periods before the sonar exercises to the behaviour of dolphins from periods during or after the exercise at the same locations.