Long latency auditory evoked potentials and object-related negativity based on harmonicity in hearing-impaired...

Hearing-impaired children (HIC) have difficulty understanding speech in noise, which may be due to difficulty parsing concurrent sound object based on harmonicity cues. Using long latency auditory evoked potentials (LLAEPs) and object-related negativity (ORN), a neural metric of concurrent sound segregation, this study investigated the sensitivity of HIC in processing harmonic relation. The participants were 14 normal-hearing children (NHC) with an average age of 7.82 ± 1.31 years and 17 HIC with an average age of 7.98 ± 1.25 years. They were presented with a sequence of 200 Hz harmonic complex tones that had either all harmonic in tune or the third harmonic mistuned by 2%, 4%, 8%, and 16% of its original value while neuroelectric brain activity was recorded. The analysis of scalp-recorded LLAEPs revealed lower N2 amplitudes elicited by the tuned stimuli in HIC than control. The ORN, isolated in difference wave between LLAEP elicited by tuned and mistuned stimuli, was delayed and smaller in HIC than NHC. This study showed that deficits in processing harmonic relation in HIC, which may contribute to their difficulty in understanding speech in noise. As a result, top-down and bottom-up rehabilitations aiming to improve processing of basic acoustic characteristics, including harmonics are recommended for children with hearing loss.