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New bioacoustic articel in J. Comp. Physiol. A

Subject: New bioacoustic articel in J. Comp. Physiol. A
From: "Sonja Amoser" <>
Date: Thu, 31 Jan 2008 09:25:08 +0100
Susanne Hoffmann, Leonie Baier, Frank Borina, Gerd Schuller, Lutz Wiegrebe and 
Uwe Firzlaff (2008): Psychophysical and neurophysiological hearing thresholds 
in the bat Phyllostomus discolor. J. Comp. Physiol. A 194(1), 39-47

Abstract: Absolute hearing thresholds in the spear-nosed bat Phyllostomus 
discolor have been determined both with psychophysical and neurophysiological 
methods. Neurophysiological data have been obtained from two different 
structures of the ascending auditory pathway, the inferior colliculus and the 
auditory cortex. Minimum auditory thresholds of neurons are very similar in 
both structures. Lowest absolute thresholds of 0 dB SPL are reached at 
frequencies from about 35 to 55 kHz in both cases. Overall behavioural 
sensitivity is roughly 20 dB better than neural sensitivity. The behavioural 
audiogram shows a first threshold dip around 23 kHz but threshold was lowest at 
80 kHz (â10 dB SPL). This high sensitivity at 80 kHz is not reflected in the 
neural data. The data suggest that P. discolor has considerably better absolute 
auditory thresholds than estimated previously. The psychophysical and 
neurophysiological data are compared to other phyllostomid bats and differences 
are discussed.

For reprints please contact Susanne Hoffmann (Email: 

Sven SchÃrnich and Lutz Wiegrebe (2008): Phase sensitivity in bat sonar 
revisited. J. Comp. Physiol. A 194(1), 61-67.

Abstract: An echolocating bat produces echoes consisting of the convolution of 
echolocation call and the impulse response (IR) of the ensonified object. A 
crucial question in animal sonar is whether bats are able to extract this IR 
from the echo. The bat inner ear generates a frequency representation of call 
and echo and IR extraction in the frequency domain requires accurate analysis 
of both magnitude and phase information. Previous studies investigating the 
phase sensitivity of bats using a jitter paradigm reported a temporal acuity 
down to 10 ns, suggesting perfect sonar phase representation. In a 
phantom-target playback experiment, we investigate the perceptual phase 
sensitivity of the bat Phyllostomus discolor using a novel approach: instead of 
manipulating IR phase by changing IR delay (jitter paradigm), we randomized IR 
phase and thus lengthened the IR over time, leaving the magnitude spectrum 
unchanged. Our results show that phase sensitivity, as reflected in the 
analysis of signal duration, appears to be much lower than phase sensitivity, 
as reflected in the analysis of signal onset. The current data indicate that 
different temporal aspects of sonar processing are encoded with very different 
temporal resolution and thus an overall claim of âphase sensitivityâ as such 
cannot be maintained.

For reprints please contact Sven SchÃrnich (Email: 

Roger D. Santer, Yoshifumi Yamawaki, F. Claire Rind and Peter J. Simmons 
(2008): Phonotactic response of female crickets on the Kramer treadmill: 
methodology, sensory and behavioural implications. J. Comp. Physiol. A 194(1), 

Abstract: Since population-level variation in female mating preferences can 
shape intraspecific communication systems within the context of sexual 
selection it is essential to quantify these preferences and their sources of 
variation. We calculated individual female response functions for four male 
calling song traits in the field cricket Gryllus bimaculatus, by performing 
untethered phonotaxis measurements on a spherical locomotor compensator (Kramer 
treadmill). Firstly, we quantify the population-level sources of phonotactic 
variation and correct for factors that adversely affect this measurement. 
Secondly, we develop methodology for the characterisation of individual female 
phonotactic response functions suitable for population-level analyses and 
demonstrate the applicability of our method with respect to recent literature 
on Orthopteran acoustic communication. Phonotaxis towards a preferred stimulus 
on different occasions is highly repeatable, with lower repeatabilities away 
from the most preferred signal traits. For certain male signal traits, female 
preference and selectivity are highly repeatable. Although phonotactic response 
magnitude deteriorated with age, preference functions of females remained the 
same during their lifetimes. Finally, the limitations of measuring phonotaxis 
using a spherical locomotor compensator are described and discussed with 
respect to the estimation of the selectivity of female response.

For reprints please contact L. Verburgt (Email: 

Kind regards

Sonja Amoser

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