The effect of broadband elicitor duration on transient-evoked otoacoustic emissions and a psychoacoustic measure of gain reduction

Abstract

Physiological and psychoacoustic studies of the medial olivocochlear reflex (MOCR) in humans have often relied on long elicitors (> 100 ms). This is largely due to previous research using otoacoustic emissions (OAEs) that found MOCR time constants in the 100s of milliseconds when elicited by broadband noise. However, Roverud and Strickland (2014), using a psychoacoustic measure of gain reduction, found differential effects of duration for on- and off-frequency tonal elicitors. For the on-frequency elicitor, thresholds increased with increasing on-frequency duration up to about 50 ms, and then plateaued. In contrast, thresholds with off-frequency elicitors continued to increase with elicitor duration. These results are consistent with cochlear gain reduction, possibly by the MOCR, in which the on-frequency elicitor is affected by gain reduction at the signal frequency place, but the off-frequency elicitor is not. The effect of the duration of broadband noise elicitors on similar psychoacoustic tasks is currently unknown. Additionally, the relationship between gain reduction measured psychoacoustically and using OAEs as a function of elicitor duration are unknown. This study will measure the effects of ipsilateral broadband noise elicitor duration on transient-evoked OAEs and psychoacoustic gain reduction estimated from a forward-masking paradigm. [Work supported by NIH R01 DC008327 (EAS) and NIH R01DC015989 (HMB).]