Variable asymmetry and resonance in the avian vocal tract: a structural basis for individually distinct vocalizations

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The social vocalizations of the oilbird (Steatornis caripensis) frequently have their acoustic energy concentrated into 3 prominent formants which appear to arise from the filter properties of their asymmetrical vocal tract with its bronchial syrinx. The frequency of the second and third formants approximate the predicted fundamental resonances of the unequal left and right cranial portions of each primary bronchus, respectively. Reversibly plugging either bronchus eliminates the corresponding formant. The first formant may arise in the trachea. The degree of vocal tract asymmetry varies between individuals, endowing them with different formant frequencies and providing potential acoustic cues by which individuals of this nocturnal, cave dwelling species may recognize each other in their dark, crowded colonies.

Original languageEnglish (US)
Pages (from-to)457-466
Number of pages10
JournalJournal of Comparative Physiology A
Issue number4
StatePublished - Oct 1 1994



  • Acoustic communication
  • Formant frequency discrimination
  • Oilbird
  • Speaker identification
  • Vocal tract filtering

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Neuroscience(all)
  • Physiology (medical)
  • Physiology
  • Animal Science and Zoology

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