Journal of Comparative Physiology A

, Volume 194, Issue 7, pp 665–683

Otoacoustic emissions in humans, birds, lizards, and frogs: evidence for multiple generation mechanisms

  • Christopher Bergevin
  • Dennis M. Freeman
  • James C. Saunders
  • Christopher A. Shera
Original Paper

DOI: 10.1007/s00359-008-0338-y

Cite this article as:
Bergevin, C., Freeman, D.M., Saunders, J.C. et al. J Comp Physiol A (2008) 194: 665. doi:10.1007/s00359-008-0338-y


Many non-mammalian ears lack physiological features considered integral to the generation of otoacoustic emissions in mammals, including basilar-membrane traveling waves and hair-cell somatic motility. To help elucidate the mechanisms of emission generation, this study systematically measured and compared evoked emissions in all four classes of tetrapod vertebrates using identical stimulus paradigms. Overall emission levels are largest in the lizard and frog species studied and smallest in the chicken. Emission levels in humans, the only examined species with somatic hair cell motility, were intermediate. Both geckos and frogs exhibit substantially higher levels of high-order intermodulation distortion. Stimulus frequency emission phase-gradient delays are longest in humans but are at least 1 ms in all species. Comparisons between stimulus-frequency emission and distortion-product emission phase gradients for low stimulus levels indicate that representatives from all classes except frog show evidence for two distinct generation mechanisms analogous to the reflection- and distortion-source (i.e., place- and wave-fixed) mechanisms evident in mammals. Despite morphological differences, the results suggest the role of a scaling-symmetric traveling wave in chicken emission generation, similar to that in mammals, and perhaps some analog in the gecko.


OAE Non-mammal Lizard Chicken Frog 

List of symbols


emission phase-gradient delay


auditory nerve fiber


amphibian papilla


basilar membrane


basilar papilla


distortion-product otoacoustic emission


evoked otoacoustic emission


quality factor


stimulus-frequency otoacoustic emission


spontaneous otoacoustic emission


tectorial membrane

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Christopher Bergevin
    • 1
    • 2
  • Dennis M. Freeman
    • 3
  • James C. Saunders
    • 4
  • Christopher A. Shera
    • 5
    • 6
  1. 1.Speech and Hearing Bioscience and Technology Program, Harvard-Massachusetts Institute of Technology Division of Health Sciences and TechnologyCambridgeUSA
  2. 2.Department of MathematicsUniversity of ArizonaTucsonUSA
  3. 3.Department of Electrical Engineering and Computer ScienceMassachusetts Institute of TechnologyCambridgeUSA
  4. 4.Department of OthorhinolaryngologyUniversity of PennsylvaniaPhiladelphiaUSA
  5. 5.Eaton-Peabody Laboratory of Auditory PhysiologyMassachusetts Eye & Ear InfirmaryBostonUSA
  6. 6.Department of Otology & LaryngologyHarvard Medical SchoolBostonUSA

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