[MARMAM] New paper on harbor porpoise echolocation
jens.koblitz at gmail.com
Thu Mar 15 14:16:57 PDT 2012
I am pleased to announce the publication of the following paper in the
Journal of the Acoustical Society of America:
Koblitz, J.C., M. Wahlberg, P. Stilz, P.T. Madsen, K. Beedholm, and
H.-U. Schnitzler (2012).
Asymmetry and dynamics of a narrow sonar beam in an echolocating
Journal of the Acoustical Society of America. 131 (3), 2315-2324
A key component in the operation of a biosonar system is the radiation
of sound energy from the sound producing head structures of toothed
whales and microbats. The current view involves a fixed transmission
aperture by which the beam width can only change via changes in the
of radiated clicks. To test that for a porpoise, echolocation clicks
were recorded with high angular resolution using a 16 hydrophone array.
The beam is narrower than previously reported (DI = 24 dB) and slightly
dorso-ventrally compressed (horizontal -3 dB beam width: 13°, vertical
-3 dB beam width: 11°). The narrow beam indicates that all smaller
toothed whales investigated so far have surprisingly similar beam widths
across taxa and habitats. Obtaining high directionality may thus be at
least in part an evolutionary factor that led to high centroid
frequencies in a group of smaller toothed whales emitting narrow band
high frequency clicks. Despite the production of stereotyped narrow band
high frequency clicks, changes in the directionality by a few degrees
were observed, showing that porpoises can obtain changes in sound radiation.
Please feel free to contact me for a pdf copy.
With kind regards,
Jens.Koblitz at uni-tuebingen.de
Insitue for Neurobiology
University of Tuebingen
Auf der Morgenstelle 28
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