Aging of the medial olivocochlear reflex and associations with speech perception

Abstract

The medial olivocochlear reflex (MOCR) modulates cochlear amplifier gain and is thought to facilitate the detection of signals in noise. High-resolution distortion product otoacoustic emissions (DPOAEs) were recorded in teens, young, middle-aged, and elderly adults at moderate levels using primary tones swept from 0.5 to 4 kHz with and without a contralateral acoustic stimulus (CAS) to elicit medial efferent activation. Aging effects on magnitude and phase of the 2f1-f2 DPOAE and on its components were examined, as was the link between speech-in-noise performance and MOCR strength. Results revealed a mild aging effect on the MOCR through middle age for frequencies below 1.5 kHz. Additionally, positive correlations were observed between strength of the MOCR and performance on select measures of speech perception parsed into features. The elderly group showed unexpected results including relatively large effects of CAS on DPOAE, and CAS-induced increases in DPOAE fine structure as well as increases in the amplitude and phase accumulation of DPOAE reflection components. Contamination of MOCR estimates by middle ear muscle contractions cannot be ruled out in the oldest subjects. The findings reiterate that DPOAE components should be unmixed when measuring medial efferent effects to better consider and understand these potential confounds.

Concurrent measures of contralateral suppression of transient-evoked otoacoustic emissions and of auditory steady-state responses

“…In normal-hearing individuals, the amount of MOC activity is moderately correlated with the ability to understand speech in the presence of background noise (Giraud et al, 1997;Kumar and Vanaja, 2004;de Boer and Thornton, 2008;Abdala et al, 2014;Mishra and Lutman, 2014;Bidelman and Bhagat, 2015), lending further support to the hypothesis that the efferent system aids with hearing in noise. Clinical populations, such as hearing-impaired individuals, often experience significant difficulties communicating in background noise.…”

Influence of the stimulus presentation rate on medial olivocochlear system assays

“…A cut-off value of 1.4% (0.12 dB) increase in stimulus pressure during elicitor-on condition with reference to elicitor-off condition has been suggested as a possible indication of MEMR activation. [21][22][23] To test for such changes in stimulus pressure, the method employed in the current study examined the first FIG. 1.…”

Medial Efferent Mechanisms in Children with Auditory Processing Disorders

“…Current understanding of the role of the MOC efferents in auditory perception in children is sparse. Limited data exist showing the relationship between the MOC reflex and speech perception in noise in 10–12-year-old (Kumar and Vanaja, 2004 ) and 13–17-year-old children (Abdala et al, 2014 ). It is expected that future studies along these lines will use state-of-the-art OAE–MOC tests that would not only help underpin the mechanisms of APD, but would also enhance the current understanding of the functional significance of the MOC system during development.…”

“…Animal work suggest a “MOC unmasking” hypothesis in which stimulation of the MOC efferents reduces cochlear responses to continuous noise, allowing greater responsiveness to transient signals embedded in noise (Winslow and Sachs, 1988 ; Kawase and Liberman, 1993 ; Kawase et al, 1993 ). While a complete understating of the role of the human MOC system in hearing is emerging (Guinan, 2006 , 2010 ), one of the putative functions of this system is to aid in listening-in-noise (Andéol et al, 2011 ; de Boer et al, 2012 ; Abdala et al, 2014 ; Mishra and Lutman, 2014 ).…”