Immittance and otoacoustic emissions in rhesus monkeys and humans

The purpose of this study was to compare multifrequency tympanometry and ot oacoustic emissions (OAEs) in rhesus monkeys (Macaca mulatta) and humans. T ympanometry and OAEs can be recorded efficiently in Macaca mulatta to asses s peripheral auditory function with results comparable to those in humans. Differences include(1) greater admittances and conductances in humans from 226 to 630 Hz, the frequency range validly assessed; (2) larger amplitude t ransient evoked OAEs (TEOAEs) and noise levels in humans; (3) larger amplit ude monkey 2f(1)-f(2) distortion product OAEs (DPOAES) (f(2)s>2 kHz); (4) m ore prominent DPOAEs other than 2f(1)-f(2) in monkeys; (5) more narrowly tu ned human f(2)/f1 X 2f(1)-f(2) amplitude functions at the lower frequencies tested; and (6) lower 2f(1)-f(2) DPOAE thresholds at f(2)=0.5 kHz and grea ter than or equal to 8 kHz in monkeys.