LAUSR

Investigations of cochlear synaptopathy in living humans rely on proxy measures of auditory nerve function. Numerous procedures have been developed, typically based on the auditory brainstem response (ABR), envelope-following response (EFR), or middle-ear muscle reflex (MEMR). Some metrics correlate with synaptic survival in animal models, but translation between species is not straightforward; measurements in humans likely reflect greater error and greater variability from non-synaptopathic sources. The present study assessed the reliability of seven measures, as well as testing for correlations between them. Thirty-one normally hearing young women underwent repeated measurements of ABR wave I amplitude, ABR wave I growth with level, ABR wave V latency shift in noise, EFR amplitude, EFR growth with stimulus modulation depth, MEMR threshold, and an MEMR difference measure. Intraclass correlation coefficients indicated good-to-excellent reliability for the raw ABR and EFR amplitudes, and for both MEMR measures. The ABR and EFR difference measures exhibited poor-to-moderate reliability. No significant correlations, nor any consistent trends, were observed between measures, providing no indication that the between-subject variability in responses are due to the same underlying physiological processes. Findings suggest that proxy measures of cochlear synaptopathy should be regarded with caution, at least when employed in young, normally hearing adults.Investigations of cochlear synaptopathy in living humans rely on proxy measures of auditory nerve function. Numerous procedures have been developed, typically based on the auditory brainstem response (ABR), envelope-following response (EFR), or middle-ear muscle reflex (MEMR). Some metrics correlate with synaptic survival in animal models, but translation between species is not straightforward; measurements in humans likely reflect greater error and greater variability from non-synaptopathic sources. The present study assessed the reliability of seven measures, as well as testing for correlations between them. Thirty-one normally hearing young women underwent repeated measurements of ABR wave I amplitude, ABR wave I growth with level, ABR wave V latency shift in noise, EFR amplitude, EFR growth with stimulus modulation depth, MEMR threshold, and an MEMR difference measure. Intraclass correlation coefficients indicated good-to-excellent reliability for the raw ABR and EFR amplitudes, and for both MEMR meas...