p a p e r s
p r e s e n t a t i o n s

Vassilakis, P.N and Narins, P.M. (2003).  Evoked otoacoustic emissions provide clues to hearing mechanisms in the frog.  J. Acoust. Soc. Am., 114(4/2): 2414 (presented at the 146th meeting of the Acoustical Society of America, Austin, TX & the 33rd annual meeting of the Society for Neuroscience, New Orleans, LA poster C388.1, 27.).


Cubic distortion product otoacoustic emissions (DPOAEs) were recorded from 10 Rana pipiens and 10 Rana catesbeiana, 5 males and 5 females each. The I/O curves obtained from the amphibian papilla (AP) of both species are very similar to the respective mammalian curves, indicating that, like in the mammalian cochlea, there may be an amplification process active in the frog AP. The DPOAE level dependence on primary levels is also similar to the mammalian case, suggesting a mechanical structure in the frog inner ear may be functioning analogously to the mammalian basilar membrane. DPOAE audiograms were obtained for primary frequencies spanning the animalsí hearing range and levels determined by the previous experiments. R.catesbeiana produce stronger emissions than R.pipiens and, consistent with previously reported sexual dimorphism in the mammalian and anuran auditory systems, females from both species produce stronger emissions than males.
Additionally, the 2f1-f2 DPOAE is generated primarily at the DPOAE frequency place, while the 2f2-f1 DPOAE is generated primarily at a frequency place between the primaries. This difference in mammalian and frog DPOAEs may be linked to an anatomical difference that results in the acoustic energy following opposite paths through the mammalian and frog inner ears. [Work supported by NIH grant No.DC-00222 to Peter M. Narins.]