spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online March 16, 2007
Journal of Experimental Biology 210, 1116-1122 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02734
This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nachtigall, P. E.
Right arrow Articles by Yuen, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nachtigall, P. E.
Right arrow Articles by Yuen, M.

Polar bear Ursus maritimus hearing measured with auditory evoked potentials

Paul E. Nachtigall1,*, Alexander Y. Supin2, Mats Amundin3, Bengt Röken3, Thorsten Møller3, T. Aran Mooney1, Kristen A. Taylor1 and Michelle Yuen1,4

1 Marine Mammal Research Program, Hawaii Institute of Marine Biology, University of Hawaii, HI, USA
2 Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia
3 Kolmården Djurpark, Kolmården, Sweden
4 National Marine Fisheries Service, Pacific Islands Regional Office, Honolulu, HI, USA


Figure 1
View larger version (10K):
[in this window]
[in a new window]

  		Fig. 1. (A) Stimulus waveform (the example is a 4-kHz signal). (B) Frequency spectra of the stimulus. Solid line, electrical signal; broken line, reproduction with frequency–response irregularity of the speaker 16 dB/octave; frequency is presented in multiples of the carrier frequency f. Straight lines in B show the spectrum width at a level of 0.5 (–3 dB) re maximum.

 

Figure 2
View larger version (144K):
[in this window]
[in a new window]

  		Fig. 2. Experimental set-up. 1, active electrode; 2, reference electrode; 3, grounding; 4, speaker.

 

Figure 3
View larger version (7K):
[in this window]
[in a new window]

  		Fig. 3. Frequency spectrum of the ambient noise. Spectrum power is specified in SPL of half-octave bands. The straight lines with a slope of –3 dB/octave approximate the limits of noise fluctuation corresponding to overall noise levels of 62 and 72 dB SPL.

 

Figure 4
View larger version (28K):
[in this window]
[in a new window]

  		Fig. 4. (A) Examples of auditory evoked potential (AEP) waveforms to stimuli of 4 kHz carrier frequency at various intensities (dB SPL). (B) Cross-correlation functions (CCFs) between the corresponding waveforms and a standard AEP waveform obtained at high (110 dB) stimulus intensity. CCFs are calibrated in RMS values within a 10-ms window. Dots in B show CCF peak positions.

 

Figure 5
View larger version (5K):
[in this window]
[in a new window]

  		Fig. 5. An example of AEP magnitude (specified as peak CCF value) dependence on stimulus intensity. The same measurements as in Fig. 3 (4-kHz carrier frequency). The straight line is the regression line for the data within a range of 70–110 dB (r2=0.94).

 

Figure 6
View larger version (12K):
[in this window]
[in a new window]

  		Fig. 6. (A) Individual audiograms for the three polar bears in the ambient noise conditions. (B) The inter-individual averaged audiogram (mean), its correction for a 300 ms temporal summation (corr 300 ms), and limits of ambient noise fluctuations corresponding to overall noise levels of 62 and 72 dB (noise 62 and noise 72).

 




© The Company of Biologists Ltd 2007