Auditory Middle Latency Response in Children with and Without Dichotic Deficits

Amblyaudia (AMB) and dichotic dysaudia (DD) are distinct subtypes of dichotic listening deficits characterized by different behavioral profiles. AMB is associated with marked interaural asymmetry, whereas DD is defined by bilaterally poor but relatively symmetric performance. The present study investigated whether these behavioral distinctions are reflected in the auditory middle latency response (MLR). Specifically, we examined whether children with AMB exhibit asymmetric MLR patterns and whether children with DD demonstrate more symmetric responses, relative to typically performing (TYP) peers.

Thirty-seven children aged 9-12 years with normal peripheral hearing were recruited through clinical referrals and community outreach. Participants were classified as AMB, DD, or TYP based on performance on standardized dichotic listening measures. MLRs were recorded in response to monaural click stimulation delivered to each ear at both slow and fast presentation rates. Peak-to-peak Na-Pa amplitude and latency were analyzed to assess ear- and electrode-related effects across groups.

Children with AMB showed significant ear effects, with larger Na-Pa amplitudes elicited by left-ear stimulation, particularly at electrode C4, consistent with their behavioral asymmetry. In contrast, the DD group exhibited minimal amplitude asymmetry but showed prolonged Na-Pa latencies for right-ear stimulation at faster presentation rates. TYP children demonstrated small, expected asymmetries without significant latency delays. No reliable electrode effects were observed across groups.

The MLR differentiated between subtypes of dichotic listening deficits in ways that paralleled behavioral performance, with amplitude asymmetry characterizing AMB and rate-dependent latency differences observed in DD. These findings suggest that the MLR may provide complementary, objective information relevant to the characterization of distinct dichotic listening profiles in children.