The materials and methods paper found below may be of
interest to those who study toothed whale echolocation or use passive acoustic
monitoring at sea.
Best,
Requests for reprints can be directed to
Or
Recording and quantification of ultrasonic
echolocation clicks from free-ranging toothed whales
P.T.
Madsen
a,
b,
,
and
M. Wahlberga,
c
aZoophysiology, Department of Biological Sciences,
Build. 1131, University of Aarhus, Denmark
bWoods Hole Oceanographic Institution, Woods Hole,
MA 02543, USA
cFjord & Bælt, Margrethes Plads 1, 5300
Kerteminde, Denmark
Received 8 October 2006; revised 15 March 2007; accepted 2 April
2007. Available online 18 May 2007.
Toothed whales
produce short, ultrasonic clicks of high directionality and source level to
probe their environment acoustically. This process, termed echolocation, is to
a large part governed by the properties of the emitted clicks. Therefore
derivation of click source parameters from free-ranging animals is of
increasing importance to understand both how toothed whales use echolocation in
the wild and how they may be monitored acoustically. This paper addresses how
source parameters can be derived from free-ranging toothed whales in the wild
using calibrated multi-hydrophone arrays and digital recorders. We outline the
properties required of hydrophones, amplifiers and analog to digital
converters, and discuss the problems of recording echolocation clicks on the
axis of a directional sound beam. For accurate localization the hydrophone
array apertures must be adapted and scaled to the behavior of, and the range
to, the clicking animal, and precise information on hydrophone locations is
critical. We provide examples of localization routines and outline sources of
error that lead to uncertainties in localizing clicking animals in time and
space. Furthermore we explore approaches to time series analysis of discrete
versions of toothed whale clicks that are meaningful in a biosonar context.
Keywords: Toothed whale; Ultrasound; Recording; Click; Hydrophone; Array;
Echolocation
Zoophysiology, Dept. of Biological Sciences
Build.
8000 Aarhus