PROJECT SUMMARY/ ABSTRACT Auditory deprivation during childhood has serious consequences on all aspects of development. Otitis media (OM) is a highly prevalent condition in young children. It is principally important to examine the relationship between OM, hearing loss, and listening development to understand the functional sequelae of OM. Currently, it is difficult to ascertain the link between early childhood OM and developmental alterations in perception and listening because the available evidence is limited and is based on cross-sectional studies. The overarching goal of this project is to understand the residual effects of early childhood OM on functional listening development. In Aim 1, we will examine the effects of OM on the development of spatial listening skills after the OM is resolved. We will also examine the effect of resolved OM on the development of energetic and informational masking. In Aim 2, we will measure the sensitivity to frequency modulation and temporal gap detection to track the residual developmental effects of OM on basic auditory perceptual skills. In Aim 3, we will profile listening and communication abilities, and model listening development to define its trajectory following resolved OM in relationship to several predictors (e.g., OM history, hearing, cognition, etc.) using machine learning. In our approach, we will follow young children individually, with responses recorded longitudinally on experimental measures, and routinely document the middle ear status. The proposed work combines laboratory-based and real-world measures and carefully considers auditory, cognitive, language/literacy, and other factors for measuring functional listening skills comprehensively. Since listening is critical for language and learning in the classroom, the outcomes of this proposal are essential to understand the residual effects of OM on childhood development. This will improve our scientific and clinical knowledge about the developmental effects of OM, influencing the fields of audiology, pediatrics, speech-language pathology, otolaryngology, neuroscience, and early intervention.