The electrophysiological masking level difference: effects of age and mediation of hearing and cognition

Abstract

Objective Evaluate the conceptual framework that age effects on the electrophysiological binaural masking level difference (MLD) are partially mediated by age-related hearing loss and/or global cognitive function via mediation analysis. Design Participants underwent a series of audiometric tests. The MLD was measured via cortical auditory evoked potentials using a speech stimulus (/ɑ/) in speech-weighted background noise. We used mediation analyses to determine the total effect, natural direct effects, and natural indirect effects, which are displayed as regression coefficients ([95% CI]; p value). Study sample Twenty-eight individuals aged 19–87 years (mean [SD]: 53.3 [25.2]), recruited from the community. Results Older age had a significant total effect on the MLD (-0.69 [95% CI: −0.96, −0.45]; p < 0.01). Neither pure tone average (-0.11 [95% CI: −0.43, 0.24; p = 0.54] nor global cognitive function (-0.02 [95% CI: −0.13, 0.02]; p = 0.55) mediated the relationship of age and the MLD and effect sizes were small. Results were insensitive to use of alternative hearing measures or inclusion of interaction terms. Conclusions The electrophysiological MLD may be an age-sensitive measure of binaural temporal processing that is minimally affected by age-related hearing loss and global cognitive function.