Dear colleagues,
The following paper has just been published online in PlosONE:
Li S, Nachtigall PE, Breese M, Supin AY (2012) Hearing Sensation Levels of
Emitted Biosonar Clicks in an Echolocating Atlantic Bottlenose Dolphin. PLoS
ONE 7(1): e29793. doi:10.1371/journal.pone.0029793
Contact:
Abstract
Emitted biosonar clicks and auditory evoked potential (AEP) responses triggered
by the clicks were synchronously recorded during echolocation in an Atlantic
bottlenose dolphin (Tursiops truncatus) trained to wear suction-cup EEG
electrodes and to detect targets by echolocation. Three targets with target
strengths of −34, −28, and −22 dB were used at distances of 2 to 6.5 m for each
target. The AEP responses were sorted according to the corresponding emitted
click source levels in 5-dB bins and averaged within each bin to extract
biosonar click-related AEPs from noise. The AEP amplitudes were measured
peak-to-peak and plotted as a function of click source levels for each target
type, distance, and target-present or target-absent condition. Hearing
sensation levels of the biosonar clicks were evaluated by comparing the
functions of the biosonar click-related AEP amplitude-versus-click source level
to a function of external (in free field) click-related AEP
amplitude-versus-click sound pressure level. The results indicated that the
dolphin's hearing sensation levels to her own biosonar clicks were equal to
that of external clicks with sound pressure levels 16 to 36 dB lower than the
biosonar click source levels, varying with target type, distance, and
condition. These data may be assumed to indicate that the bottlenose dolphin
possesses effective protection mechanisms to isolate the self-produced intense
biosonar beam from the animal's ears during echolocation.
The paper is free access at:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029793
All the best
Songhai Li Ph.D.
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