Speech perception deficits and neural network alterations during cocktail-party listening in age-related hearing loss.

Age-related hearing loss (ARHL) is associated with difficulty understanding speech in complex listening environments, yet its neural basis remains unclear. We combined behavioral measures with functional near-infrared spectroscopy (fNIRS) to examine speech perception and neural responses during cocktail-party listening. Sixty-eight participants (Young-NH, Older-NH, ARHL) completed a spatialized speech-recognition task under different masker types and signal-to-noise ratios, together with resting-state and task-based fNIRS recordings. ARHL showed poorer speech perception and reduced self-reported hearing ability across listening conditions. At rest, ARHL exhibited increased frontotemporal connectivity and greater local network organization. During the task, cortical responses showed a group gradient, with attenuation in Older-NH and predominantly negative responses in ARHL, and diminished modulation by listening demands. In addition, brain-behavior coupling observed in Young-NH was absent in both older groups. These findings indicate that speech perception deficits in ARHL are associated with altered neural responses and reduced flexibility in adapting to listening demands, accompanied by disrupted brain-behavior relationships.