Low-frequency distortion product otoacoustic emissions in two species of kangaroo rats: implications for auditory sensitivity.
Low-frequency distortion-product otoacoustic emissions were measured in two species of kangaroo rats to test the prediction that a large footdrumming species (e.g., Dipodomys spectabilis) would have greater distortion-product otoacoustic emission amplitude than a small non-footdrumming species (e.g., Dipodomys merriami), indicating better hearing sensitivity at low frequencies. Equal-level (65 dB SPL) stimulus tones ( f(1), f(2)), presented over a ( f(1)) range of 200-1000 Hz, were used to evoke the 2 f(1)- f(2) distortion-product otoacoustic emission. Mean 2 f(1)- f(2) levels for D. merriami showed good correspondence to previously published audiograms for that species. Mean 2 f(1)- f(2) levels and 95% confidence intervals indicated species differences below 400 Hz, supporting the theory that low-frequency hearing sensitivity is better in large kangaroo rat species. These results suggest that the size-related divergence in footdrumming behavior may be related to differential auditory sensitivity.
Shaffer
L A
LA
Department of Audiology and Speech Sciences, Heavilon Hall, Purdue University, West Lafayette, IN 47907, USA. lashaffer@bsu.edu
Long
G R
GR
D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D001309:Auditory Threshold / Q000502:physiology*; D004173:Dipodomys / Q000502:physiology*; D005260:Female; D008297:Male; D014828:Vocalization, Animal / Q000502:physiology*