Nearly 40% of children with hearing loss have a secondary disability, yet audiologists lack the appropriate behavioral assessment procedures to measure hearing in children with diverse or complex developmental profiles. The long-term goal of this line of research is to improve hearing health care for children with developmental disabilities by transforming behavioral hearing testing methods. The overall objectives for this application are to identify gaps in current clinical care and to isolate methodological and child factors that affect behavioral data. Our central hypothesis is that the inability to obtain accurate and reliable behavioral thresholds with current behavioral procedures reflects methodology limitations, not limitations of the child. The rationale for this work is that by isolating factors that affect threshold we can develop rigorous methods that overcome the limitations of current clinical practices; thereby, improving hearing health care for children with developmental disabilities. The central hypothesis will be tested by pursuing two specific aims: (1)!identify gaps in the current state of clinical assessment practices for children with developmental disabilities; and (2) identify factors that influence behavioral threshold accuracy. Under the first aim, big data analytics with a publicly-available database will be used to assess the current clinical situation. For the second aim, using a novel observer-based psychoacoustics procedure, we will evaluate methodological and child factors that are expected to affect behavioral data from 1.5- to 5-year-old children with different developmental status (Autism Spectrum Disorder, Down syndrome, or typical development). The research proposed in this application is innovative, in the applicant’s opinion, because it (1) harnesses the power of big data analytics to accelerate the pace of research in pediatric audiology, and (2) it uses an observer-based procedure that overcomes the challenges associated with collecting and interpreting data from children with developmental disabilities. The proposed work is significant because it will provide strong scientific evidence for modifying current clinical procedures for children with developmental disabilities and for developing much-needed methodology advancements essential to eliminating existing hearing health care disparities.!