Hearing Aids Reshape Neural Processing of Emotional Speech Without Improving Emotion Perception

Hearing aids have improved speech intelligibility but not speech emotion perception in older adults with hearing loss. Hearing loss has also been linked to altered brain responses to emotional non-speech sounds, potentially contributing to the speech emotion perception deficits even under aided listening. While fMRI requires hearing aid removal due to metal incompatibility, fNIRS is silent and hearing-aid compatible, creating a novel opportunity to identify neural processes during aided listening. We leveraged fNIRS to examine how hearing aids affect brain function in experienced hearing-aid users during speech emotion perception. Older adults (17 normal hearing, 14 hearing-aid users) judged vocal-emotion changes in speech while fNIRS recorded hemodynamic activity. Hearing-aid users completed the task under aided and unaided listening. Behaviorally, hearing aids did not improve speech emotion perception, replicating prior research. In cortical responses, individuals with hearing loss showed increased planum temporale activity, regardless of hearing-aid use. Unaided listening showed additional frontal recruitment, including increased medial superior frontal gyrus activity and stronger functional connectivity between inferior frontal and superior temporal gyri. Conversely, aided listening increased inferior parietal lobe activity, but reduced connectivity between inferior frontal gyrus and inferior parietal lobe. Together, findings indicate that hearing aids partially modify cortical processing of emotional speech. They reduced reliance on frontal compensatory control systems and increased engagement of a higher-order parietal region, consistent with partial restoration of bottom-up auditory information during aided listening. Persistent abnormalities in early auditory processing and incomplete sensorimotor integration may explain why hearing aids fail to normalize speech emotion perception.