Effects of childhood hearing loss on the subcortical and cortical representation of speech

Little is known about the effects of childhood mild-to-moderate sensorineural hearing loss (MM HL) on the function of the auditory pathway. We aimed to examine the effect of childhood MM HL and the benefit of frequency-specific amplification on both subcortical and cortical auditory processing, and to relate it to speech-perceptual abilities. We recorded subcortical and cortical responses to speech syllables in nineteen children with congenital MM HL (unamplified and amplified), and sixteen children with typical hearing (unamplified sounds only). Speech perception was measured behaviourally. Congenital HL led to smaller subcortical and cortical responses to unamplified speech sounds. There was a significant benefit of amplification on subcortical and early, but not late, cortical responses, with some effects differing across age. No relationship was found between the neural and behavioural measures. Childhood MM HL affects both subcortical and cortical processing of speech. Amplification mostly benefits subcortical processing of speech in younger children. Childhood HL leads to functional changes in the processing of sounds, with amplification differentially affecting subcortical and cortical levels of the auditory pathway.