Auditory-cognitive training is associated with selective reorganization of alpha-band connectivity during speech-in-noise comprehension.
TL;DR
A link between stronger post-training connectivity in control-related pathways and better SiN comprehension accuracy under noisy listening conditions is suggested, while the pathway-specific pattern remains exploratory pending larger, preregistered studies.
Abstract
Older adults with hearing loss often struggle to understand speech in background noise because degraded auditory input increases demand on attention, working memory, and control. Auditory-cognitive training (ACT) can improve speech-in-noise (SiN) comprehension, but whether such gains are accompanied by changes in large-scale neural connectivity remains poorly understood. We tested whether ACT was associated with pre-to-post changes in source-space alpha-band phase synchrony within an auditory-control network during continuous SiN comprehension, and whether such changes related to ACT-associated behavioural gains. Fifty-four native German-speaking older adults with mild-to-moderately severe sensorineural hearing loss completed either ACT or an active control intervention and underwent electroencephalography while listening to continuous speech in no-noise, low-noise (+8 dB signal-to-noise ratio, SNR), and high-noise (+3 dB SNR) conditions. We quantified alpha-band phase synchrony (8-12 Hz) between a priori pathways linking auditory-related/posterior temporal, inferior frontal, dorsolateral prefrontal, superior parietal, and dorsal anterior cingulate regions. In an exploratory pathway-wise screen, ACT was associated with pre-to-post changes in alpha-band phase synchrony in two left-lateralized pathways under no-noise and one left- and one right-lateralized pathway under low-noise, with no corresponding high-noise changes. Among the pathways identified in this screen, stronger post-training alpha-band phase synchrony in cingulate-prefrontal and parietal-prefrontal pathways was associated with better SiN comprehension accuracy under noisy listening conditions. These findings indicate that behavioural improvement was accompanied by condition-specific changes in alpha-band connectivity. They suggest a link between stronger post-training connectivity in control-related pathways and better SIN comprehension, while the pathway-specific pattern remains exploratory pending larger, preregistered studies.