Using a simple model of the birds' binaural pressure difference acoustic receivers it was predicted that the interaural delay achieved by birds at low frequencies is far greater than that of mammals with a similar head-size. This was upheld when interaural delay was recorded, between the cochlear microphonics, for six species. Stimulus positions were varied over the azimuthal range from the frontal midline to the interaural axis. Predicted delays were frequency dependent (higher frequency, smaller delay), as were the actual delays, and the magnitude of the measured delays were comparable with predictions. Delays measured at high frequencies were close to those expected from pathlength around the head, but delays measured at low frequencies could be more than three times this expectation. This finding raises the possibility that interaural delay may be a useful localization cue in birds, even for those species with very small heads, since the large delays at low frequencies are sufficient to provide a physiological cue to azimuth. © 1988 Springer-Verlag.

Item Type:	Refereed Article
Keywords:	animal cell; animal experiment; auditory frequency; bird; controlled study; hearing; nonhuman
Research Division:	Medical and Health Sciences
Research Group:	Neurosciences
Research Field:	Neurology and Neuromuscular Diseases
Objective Division:	Health
Objective Group:	Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:	Nervous System and Disorders
Author:	Calford, MB (Professor Mike Calford)
ID Code:	91257
Year Published:	1988
Web of Science® Times Cited:	52
Deposited By:	Research Division
Deposited On:	2014-05-13
Last Modified:	2014-05-13
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