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THE MAXIMUM RANGE OF VOCAL COMMUNICATION IN AIR BETWEEN A HARBOR SEAL ( PHOCA VITULINA ) PUP AND ITS MOTHER
Author(s) -
Reiman A. J.,
Terhune J. M.
Publication year - 1993
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/j.1748-7692.1993.tb00442.x
Subject(s) - phoca , bay , sound transmission class , transmission loss , range (aeronautics) , sound (geography) , underwater , environmental science , transmission (telecommunications) , noise (video) , acoustics , geology , atmospheric sciences , oceanography , physics , materials science , telecommunications , ecology , biology , image (mathematics) , artificial intelligence , computer science , composite material
The transmission losses with distance of four pure tones (0.5, 1, 2, 4 kHz) were measured in the air 9 cm above the surface of the coastal waters in the Bay of Fundy. The study was conducted between May and July 1992, on warm days with low winds. The measured transmission losses were as much as 11 dB less than predicted by spherical spreading (6 dB/distance doubled), at 400 m (0.5 kHz). This enhanced sound transmission is probably due to the air temperature profile which increases with height above the water's surface. Such a profile causes sound waves to refract towards the water, thereby reducing spreading losses. High‐frequency sound absorption negates enhanced transmission at 4 kHz, at distances over 500 m. On days with low winds and low ambient noise levels, a seal pup calling at 90 dB re 20, μPa at 0.5 kHz should be detectable by the mother up to 1 km away, and may be audibly recognizable up to 140 m away.