Journal of Comparative Physiology A

, Volume 197, Issue 5, pp 541–559

Auditory fovea and Doppler shift compensation: adaptations for flutter detection in echolocating bats using CF-FM signals


DOI: 10.1007/s00359-010-0569-6

Cite this article as:
Schnitzler, HU. & Denzinger, A. J Comp Physiol A (2011) 197: 541. doi:10.1007/s00359-010-0569-6


Rhythmical modulations in insect echoes caused by the moving wings of fluttering insects are behaviourally relevant information for bats emitting CF-FM signals with a high duty cycle. Transmitter and receiver of the echolocation system in flutter detecting foragers are especially adapted for the processing of flutter information. The adaptations of the transmitter are indicated by a flutter induced increase in duty cycle, and by Doppler shift compensation (DSC) that keeps the carrier frequency of the insect echoes near a reference frequency. An adaptation of the receiver is the auditory fovea on the basilar membrane, a highly expanded frequency representation centred to the reference frequency. The afferent projections from the fovea lead to foveal areas with an overrepresentation of sharply tuned neurons with best frequencies near the reference frequency throughout the entire auditory pathway. These foveal neurons are very sensitive to stimuli with natural and simulated flutter information. The frequency range of the foveal areas with their flutter processing neurons overlaps exactly with the frequency range where DS compensating bats most likely receive echoes from fluttering insects. This tight match indicates that auditory fovea and DSC are adaptations for the detection and evaluation of insects flying in clutter.


EcholocationBatsAuditory foveaDoppler shift compensationFlutter detection



Basilar membrane


Constant frequency


Cochlear microphonics


Doppler shift


Doppler shift compensation


Frequency modulated


Horseradish peroxidase


Inferior colliculus


Evoked potentials from auditory nerve


Evoked potentials from IC

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Animal PhysiologyInstitute of Neurobiology, University of TuebingenTübingenGermany