[MARMAM] New publication on dolphin echolocation

Adam A. Pack pack at hawaii.edu
Mon Jan 22 22:07:45 PST 2007

Aloha colleagues,
For your interest, we have just published the 
following article on dolphin echolocation:

Branstetter, B. K., Mevissen S. J., Pack, A. A., 
Herman, L. M., Roberts, S. R., and Carsrud, L. K. 
(2007).  Dolphin (Tursiops truncatus) echoic 
angular discrimination:  Effects of objects 
separation and complexity.  Journal of the 
Acoustical Society of America, 121, 626-635.

Summary of article
A bottlenose dolphin was tested on its ability to 
echoically discriminate horizontal angular 
differences between arrays of vertically oriented 
air-filled PVC rods. The blindfolded dolphin was 
required to station in a submerged hoop 2  radial 
m from the stimuli and indicate if an array with 
two rods (S+) was to the right or the left of a 
single rod (S-). The angular separation between 
the two rods (thetaw) was held constant within 
each experiment while the angle between the S+ 
and the S- stimuli (thetab) varied to produce 
angular differences (Deltatheta=thetab-thetaw) 
ranging from 0.25 to 4°. In experiment I, thetaw 
was maintained at 2° and in experiment II, thetaw 
was maintained at 4°. Resulting 75% correct 
thresholds (method of constant stimuli) were 1.5 
and 0.7°, respectively. The two main findings of 
this study are: (1) decreasing the number of 
targets does not aid in localization, and (2) 
increasing the space between the rods enhances 
localization. Taken as a whole, the experiments 
suggest dolphins have a well-developed ability to 
resolve spatial information through sonar.

Reprint pdfs may be obtained from Brian 
Branstetter at branstet at hawaii.edu or from Adam 
Pack at pack at hawaii.edu.

Wishing you all a happy, healthy, and peaceful 2007,

Adam A. Pack, Ph.D.
Vice President and Research and Education Program 
Manager, The Dolphin Institute
Affiliate Graduate Faculty, University of Hawaii at Manoa
P.O. Box 700694
Kapolei, HI  96709
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