Neural signatures of disordered multi-talker speech perception in adults with normal hearing

In social settings, speech waveforms from nearby speakers mix together in our ear canals. The brain unmixes the attended speech stream from the chorus of background speakers using a combination of fast temporal processing and cognitive active listening mechanisms. Multi-talker speech perception is vulnerable to aging or auditory abuse. We found that ~10% of adult visitors to our clinic have no measurable hearing loss, yet offer a primary complaint of poor hearing. Multi-talker speech intelligibility in these adults was strongly correlated with neural phase locking to frequency modulation (FM) cues, as determined from ear canal EEG recordings. Combining neural temporal fine structure (TFS) processing with pupil-indexed measures of cognitive listening effort could predict most of the individual variance in speech intelligibility thresholds. These findings identify a confluence of disordered bottom-up and top-down processes that predict poor multi-talker speech perception and could be useful in next-generation tests of hidden hearing disorders.