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Constraints on the coding of sound frequency imposed by the avian interaural canal


Calford, MB, Constraints on the coding of sound frequency imposed by the avian interaural canal, Journal of Comparative Physiology - A Sensory, Neural, and Behavioral Physiology, 162, (4) pp. 491-502. ISSN 0340-7594 (1988) [Refereed Article]

DOI: doi:10.1007/BF00612514


Extracellular recordings were made from the midbrain auditory area to determine the limits of auditory frequency sensitivity in a variety of birds. The audiograms of some species show a consistent missing frequency range of 1/3 to 1/2 an octave, to which no neurons are tuned. All species, except owls, have a low upper frequency limit in comparison with mammals of similar headwidth. A consideration of both the upper frequency limits and the missing frequency ranges led to the conclusion that frequencies which do not generate localization cues are not represented in the midbrain. The upper frequency limit appears to match the upper limit of generation of significant interaural and monaural intensity cues to localization. The variation of these cues with frequency was examined through a simple model of the birds' sound receiving system which incorporated the interaural canal and considered the tympanic membranes as pressure difference receivers. Apart from coraciiform species, which have low upper frequency limits matching the frequency of the primary missing frequency band of other species, and owls, which have high upper frequency limits, the upper frequency limits of the birds studied are inversely related to head-width. The argument for missing frequency ranges being related to nonlocalizable frequencies is simpler, for it has been found previously, using cochlear microphonic recording, that within a bird's audiogram there are frequency regions with poor directionality cues. These regions appear to correspond to the missing frequency ranges. © 1988 Springer-Verlag.

Item Details

Item Type:Refereed Article
Keywords:animal experiment; auditory frequency; bird; controlled study; hearing; nonhuman
Research Division:Biomedical and Clinical Sciences
Research Group:Neurosciences
Research Field:Neurology and neuromuscular diseases
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Calford, MB (Professor Mike Calford)
ID Code:91258
Year Published:1988
Web of Science® Times Cited:21
Deposited By:Research Division
Deposited On:2014-05-13
Last Modified:2014-05-13

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