Reliability of distortion-product otoacoustic emissions in the common marmoset (Callithrix jacchus).

This study examines the test-retest reliability of distortion-product otoacoustic emissions (DPOAEs) in ketamine-anesthetized common marmosets (Callithrix jacchus). DPOAE gain functions were measured at 16 f(2)-frequencies between 3 and 24 kHz. Test-retest reliability was assessed at the following time intervals: (1) Interleaved, in which two gain functions were obtained at each frequency before advancing to the next frequency, (2) Immediate, wherein one gain function was collected at all f(2)-frequencies and the retest was immediately performed without removing the probe tip, (3) Short-term, in which the retest followed a 10-min period with the probe removed, and (4) Long-term, wherein the retest was performed at least one week after the initial test. Reliability was assessed using four correlation coefficients used in the literature. Test-retest reliability was best in the interleaved interval and worst in the short-term interval. In general, reliability was best when primary-tone levels were high. Correlation coefficients decreased at frequencies above 12-kHz in the short-term and long-term intervals, but the decrease was more substantial in females than in males in the long-term interval. At frequencies below 12 kHz, same-day measurements (2, 3) were less repeatable, regardless of whether the probe was removed, which may be due to time under anesthesia. These results have implications for DPOAE studies where repeated measures are required and when treatment or group differences are small.