ABOVE: Thomas Taylor and his Bear listen intently to a Humpback song aboard 'Volante II' during the 1998 Expedition.
(Photo: Trish Franklin)
|'The song (of the humpback whale) is repeated...and emitted with sound intensities of 100 to 110 decibels, that is to say, in a class with a pneumatic drill. What is most interesting in this context is that the song was heard at a depth of about 3,300 feet off the east coast of North America, which is just at the depth where we find two sound-reflecting layers close to each other. (These layers exist in all the oceans, at various depths.) Our calculations indicate that a sound of this intensity, emitted within the reflecting layers, could be heard by a human ear at a distance of well over 25,000 miles (which is the circumference of the earth). Even if we make deductions for disturbance, background noise, and the like, it appears that by seeking out this communication layer whales could call to each other over distances as great as the entire breadth of the Pacific ocean.' |
(Karl-Erik Fichtelius and Sverre Sjolander, 1973.)