Biophysics, neural processing and robotics of the lizard ear, a highly directional sensor

Authors

  • Jakob Christensen-Dalsgaard Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark

Abstract

The ear of lizards shows strongly directional responses with up to 40 dB differencesinsensitivitytoipsi-andcontralateralstimulation.Thedirectionality is generated by a simple principle: strong acoustical coupling of the eardrums through the large mouth cavity. Our laser vibrometry measurements show that the lizard ear is a two-input system with approximately 0 dB contralateral transmission gain in a 2 kHz frequency band. This transmission is boosted by resonances in the large, open tympanic cavities. Probably because of these resonances, the interaural delay is approximately three times larger than the arrival-time differences at the lizard eardrums. Since already the ear is directional, the subsequent neural processing may be much simpler than in mammals, for example, where directionality is based on neural computation. Our neurophysiological experiments show that binaural comparison is based on contralateral inhibition with no apparent segregation of time and intensity processing. This simple computation generates a strongly directional lateralization that is suf cient to orient the animal. This has been shown by robot simulations, where the ear is modelled by a simple three- impedance acoustical analog. Implementation of the model in a digital signal processor and subsequent neural processing based on binaural comparison produces a robust directional response.

References

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Additional Files

Published

2009-12-15

How to Cite

Christensen-Dalsgaard, J. (2009). Biophysics, neural processing and robotics of the lizard ear, a highly directional sensor. Proceedings of the International Symposium on Auditory and Audiological Research, 2, 29–36. Retrieved from https://proceedings.isaar.eu/index.php/isaarproc/article/view/2009-03

Issue

Vol. 2 (2009): Binaural Processing and Spatial Hearing

Section

2009/1. Physiological measures and models of binaural hearing

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