The acoustic field on the forehead of echolocating Atlantic bottlenose dolphins (Tursiops truncatus)
Au, Whitlow W. L.
Houser, Dorian S.
Finneran, James J.
Talmadge, Lois A.
Moore, Patrick W.
MetadataShow full item record
KeywordAcoustic field; Acoustic signal detection; Bioacoustics; Biocommunications; Hydrophones; Underwater sound; Zoology
Arrays of up to six broadband suction cup hydrophones were placed on the forehead of two bottlenose dolphins to determine the location where the beam axis emerges and to examine how signals in the acoustic near-field relate to signals in the far-field. Four different array geometries were used; a linear one with hydrophones arranged along the midline of the forehead, and two around the front of the melon at 1.4 and 4.2 cm above the rostrum insertion, and one across the melon in certain locations not measured by other configurations. The beam axis was found to be close to the midline of the melon, approximately 5.4 cm above the rostrum insert for both animals. The signal path coincided with the low-density, low-velocity core of the melon; however, the data suggest that the signals are focused mainly by the air sacs. Slight asymmetry in the signals were found with higher amplitudes on the right side of the forehead. Although the signal waveform measured on the melon appeared distorted, when they are mathematically summed in the far-field, taking into account the relative time of arrival of the signals, the resultant waveform matched that measured by the hydrophone located at 1 m.
Author Posting. © Acoustical Society of America, 2010. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 128 (2010): 1426-1434, doi:10.1121/1.3372643.
Suggested CitationJournal of the Acoustical Society of America 128 (2010): 1426-1434
Showing items related by title, author, creator and subject.
Foote, Kenneth G.; Hastings, Mardi C.; Ketten, Darlene R.; Lin, Ying-Tsong; Reidenberg, Joy S.; Rye, Kent (Acoustical Society of America, 2012-02)Potential physical effects of sonar transmissions on marine mammals were investigated by measuring pressure fields induced in a 119-kg, 211-cm-long, young adult male common dolphin (Delphinus delphis) cadaver. The specimen ...
Observed limiting cases of horizontal field coherence and array performance in a time-varying internal wavefield Collis, Jon M.; Duda, Timothy F.; Lynch, James F.; DeFerrari, Harry A. (Acoustical Society of America, 2008-08-28)Using a moored source and horizontal/vertical line array combination, horizontal coherence properties of high signal to noise ratio (>=20 dB) 100–1600 Hz signals have been measured. Internal waves in the area of the ...
Macpherson, Mark K.; Frisk, George V. (Woods Hole Oceanographic Institution, 1981-04)The effects of normal modes in the bottom on the acoustic field in the ocean are examined. The ocean bottom model consists of a slow isovelocity layer overlying an isovelocity half-space to simulate the characteristic sound ...