ULTRASONIC STUDIES ON HEAD OIL OF NORTH-ATLANTIC PILOT WHALE (GLOBICEPHALA MELAENA MELAENA)

Head oil extracted from a sample of the melon was studied. Sound velocity and sound absorption data were presented. Some refraction of ultrasound may occur in the melon as the sound velocity of the head oil, comprising 80% of its weight, was lower than that of sea water. The lens action of the melon seems not to be strong enough to explain the high directionality of the sound emitted in echolocation, but a cooperative refraction and reflection model was suggested. There may be a strong dependence on water temperature of the refractivity of the melon. An attempt was made to correlate the chemical composition with the sonic properties of the oil.