The relationship between the middle latency response binaural interaction component (MLR-BIC) and tests of binaural integration in young adults

Although the exact prevalence is unknown, a high comorbidity rate exists between auditory processing disorders (APD) and learning disabilities (LD). Numerous studies have shown individuals diagnosed with a LD have increased difficulty processing dichotic information. Adults who have difficulty with dichotic listening (DL) often have poor speech recognition. Behaviorally, DL deficits can be expressed as abnormal binaural integration (BI) skills as evidenced by an abnormal significant ear asymmetry or amblyaudia.;In the diagnosis of APD, current audiologic professional guidelines recommend the use of a comprehensive central auditory processing (CAP) test battery to include both behavioral and auditory electrophysiologic (AEP) measures. There are a number of commercially available behavioral tests of DL for the practicing clinician to choose from. While AEP equipment is also commercially available, there is limited information regarding the usefulness of binaural AEP measures to evaluate the central auditory nervous system (CANS).;There are two objective of this study. The first objective is to document the middle latency response binaural interaction component (BIC-Pa) of individuals with a diagnosed LD and amblyaudia as there is limited information regarding this population using this measurement technique. The second objective is to identify the relationship between commercially available behavioral tests of binaural integration (BI) and the BIC-Pa. A significant correlation was hypothesized to exist between test measures with a significant difference between participant groups.;A quasi-experimental design was employed. Twenty-three adults 21-30 years old qualified and participated in the current study. Participants were categorized in three groups (two experimental (L and LA) and one control (C)) for data analysis determined by: performance on the Randomized Dichotic Digit Test -- 2 pair and reported previous diagnosis of LD.;A repeated measures analysis of variance (ANOVA) on pooled participant data revealed a significant main effect for ear stimulated (p = .007), specifically the NaPa amplitude of the MLR (p = .017), but not group. A pairwise comparison indicated a significant difference between the peak-to-peak amplitude of the NaPa component between the monaural and true binaural waveforms. Individual group statistics revealed no significant effect for ear stimulated, however secondary analysis with a univariate test for group LA revealed a significant difference in NaPa amplitudes between the right and left ears. Statistical analysis failed to show any significant relationships between MLR amplitude measures and tests of BI. This may suggest that the tests of BI utilized in this study may tap differing anatomical sites than that of the MLR and MLR-BIC. Further investigations are warranted to evaluate the role of objective measures of the binaural auditory system in APD.