Abstract # 211:

Scheduled for Monday, September 19, 2011 09:15 AM-09:30 AM: Session 27 (Meeting Room 410) Oral Presentation


DISTORTION-PRODUCT OTOACOUSTIC EMISSIONS IN THE COMMON MARMOSET (CALLITHRIX JACCHUS): PARAMETER OPTIMIZATION AND REPEATABILITY

M. D. Valero1, E. G. Pasanen2, D. McFadden2 and R. Ratnam1,3
1University if Texas at San Antonio, Department of Biology, San Antonio, TX 78249, USA, 2University of Texas at Austin, Department of Psychology and Center for Perceptual-Systems, Austin, TX, 78705, , 3Texas Biomedical Research Institute, San Antonio, TX, 78227
line
     The common marmoset (Callithrix jacchus) is emerging as a model for hearing research, but little is known about the peripheral auditory system of this species. Here we report the optimal parameters and the repeatability of distortion-product otoacoustic emissions (DPOAEs), a non-invasive measure of cochlear function. The primary-tone frequency ratio (f2/f1) and level difference (L1–L2) was varied systematically to determine which would elicit the strongest DPOAEs at16 frequencies. The optimal f2/f1 decreased as frequency increased and levels decreased. Changing L1-L2 from 0-10 dB minimally affected DPOAEs. We assessed repeatability at four time intervals: Interleaved, wherein two gain-functions were obtained at each frequency; Immediate, wherein the retest immediately followed the initial test without probe-tip removal; Short-term, wherein the retest followed 10 minutes with probe removal; and Long-term, wherein the retest followed the test by at least one week. The best reliability was observed in the interleaved interval. In the immediate, short-term, and long-term intervals reliability increased with increasing level. At frequencies above 12-kHz, reliability was greatest when the probe tip was not removed. At frequencies lower than 6-kHz, the greatest reliability was seen when time under anesthesia was lowest. Measurements were more repeatable over time in males than in females, especially at high frequencies and low levels. These results have implications for DPOAE measurements where repeated measures are required, as when assessing aging or experimental effects.