Visual speech cues enhance neural speech tracking in right auditory cluster leading to improvement in speech in noise comprehension in older adults with hearing impairment

Abstract

Abstract Comprehending speech in noisy situations is difficult and suffers with aging, hearing loss, and cognitive decline. Using visual speech cues improves perception and comprehension of speech in noise (SiN) in older adults with hearing impairment. In the current study, we investigated neurofunctional correlates (i.e., neural tracking of speech) of the visual enhancement effect in a naturalistic setting while older adults with hearing impairment (N = 67) listened to sentences in babble noise in audio-only and audiovisual conditions and performed an intelligibility and a comprehension task, while electroencephalography (EEG) was recorded. Behaviourally, we found that visual speech cues improved intelligibility and comprehension of speech presented in babble noise and individuals with higher working memory capacity benefitted. Furthermore, we found that the visual enhancement effect was accompanied by increased cortical tracking of the speech envelope. A post hoc analysis revealed that individuals who were low performers in the audio-only condition (i.e., < 70% correct) improved in speech in noise comprehension in an audiovisual setting. Further, these low auditory-only performers showed deficient neural speech tracking in a right-hemispheric temporo-parieto-occipital, which improved significantly when visual speech cues were presented leading to more bilateral processing of speech. Overall, our results show that older adults with hearing impairment who have difficulties with speech in noise perception use visual speech cues to improve performance, which is reflected in more bilateral processing of speech.