Authors: Bharti Katbamna John A Brown Melissa Collard Charles F Ide
Publish Date: 2005/12/02
Volume: 192, Issue: 4, Pages: 381-387
Abstract
In this study we recorded auditory brainstem responses to airborne sounds to determine the hearing sensitivity of Xenopus laevis frogs and correlated their hearing profiles with middle ear characteristics In newly metamorphosed frogs body mass 05–076 gm snoutvent length 17–20 mm best hearing sensitivities were measured in the 24–28 kHz range whereas optimal hearing sensitivity of older adults body mass 18–90 gm snoutvent length 57–100 mm ranged from 10 to 12 kHz Middle ear volumes reconstructed from serial sections showed approximate volume of 0002 cc and 004–007 cc in newly metamorphosed and older frogs respectively This inverse frequency–volume relationship is consistent with the properties of an acoustic resonator indicating that differences in best hearing sensitivity are at least in part correlated to variation in middle ear volumes for airborne sounds These results are consistent with peak frequency vibrational velocity profiles of Xenopus tympanic disk that have been shown to be dependent on underlying middle ear volumes and corroborate the occurrence of peak amplitudes of otoacoustic emissions in the 10–12 kHz region in adult Xenopus frogsThe authors would like to thank Andrea Engel for her assistance in plotting the ABR data This work was supported in part by the Western Michigan University Faculty Research and Creative Activities Support Fund Award to BK and EPA grant R830235010 to CFI The experiments comply with the ‘Principles of animal care’ publication no 86–23 revised 1985 of the National Institutes of Health and also with the current laws of the country in which the experiments were performed
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