Auditory-cognitive training is associated with selective reorganization of alpha-band connectivity during speech-in-noise comprehension.

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.