Older Adults Show Preserved Neural Signatures of Audiovisual Integration but Altered Links to Speech Comprehension

In a MEG/RIFT audiovisual speech task, older adults showed preserved task-sensitive auditory, visual, and intermodulation neural responses, but the link between intermodulation coherence and comprehension benefits was absent.

• Why it matters: Older adults struggle to understand speech in noise despite relatively preserved hearing, and it was unclear whether audiovisual integration mechanisms remain intact during healthy ageing.
• What they did: Forty younger and forty older adults attended one of two competing speech streams while lip movements were frequency tagged; task relevance was manipulated via attended versus unattended speech envelope, and intermodulation coherence was related to comprehension.
• The result: Visual speech tagging improved comprehension in younger adults but not older adults; intermodulation responses stayed sensitive to task relevance across ages, yet Task-Relevant versus Task-Irrelevant intermodulation coherence predicted comprehension benefits only in younger adults.