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

Calford M.B. (1988) Constraints on the coding of sound frequency imposed by the avian interaural canal. Journal of Comparative Physiology A, 162 4: 491-502. doi:10.1007/BF00612514


Author Calford M.B.
Title Constraints on the coding of sound frequency imposed by the avian interaural canal
Journal name Journal of Comparative Physiology A   Check publisher's open access policy
ISSN 0340-7594
Publication date 1988-01-01
Sub-type Article (original research)
DOI 10.1007/BF00612514
Volume 162
Issue 4
Start page 491
End page 502
Total pages 12
Publisher Springer-Verlag
Subject 2802 Behavioral Neuroscience
2800 Neuroscience
2737 Physiology (medical)
1314 Physiology
1103 Clinical Sciences
Abstract 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.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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