PROJECT SUMMARY AND ABSTRACT Hearing loss (HL) in the first two years of life can delay language development, making early diagnosis and intervention essential in the critical 3-18 mo period. Early identification of hearing loss has a significant impact on maintaining normal language development, leading to the 1-3-6 guidelines, which recommend that infants be screened by 1 mo, diagnosed by 3 mo, and receive interventions by 6 mo. However early testing is impractical using current diagnostic tests. The standard diagnostic test, the auditory brainstem response (ABR), requires that infants be still, limiting its applicability to asleep or sedated infants: the former often yields incomplete data due to waking, while sedation is used less and less due to concerns about its impact on development. Further, physiologic tests of hearing such as OAE and ABR only test for deficits in part of the auditory pathway, and miss deficits in the central auditory nervous system. Finally, the decision process using ABR is subjective, lacking a statistical basis for diagnosing HL. A survey of pediatric audiologists in Western US revealed that given the limitations of current tests, there is an urgent need for an alternative method of assessing infant hearing that is simple, quick, sedation-less, and objective. Perceptivo proposes a new hearing test based on the sound-elicited pupil dilation response (PDR). PDR is enabled by advances in software and hardware, as well as methodological innovations that enabled highly precise video tracking of pupil size in head-free infants. Infants in the relevant 3-18 mo range exhibit a strong and consistent PDR to tones at an age when speech is rapidly developing. The infant PDR assay will leverage preliminary data from 41 normal hearing infants, and the team’s considerable experience in using pupil dilation to assess sensation in non-humans and adult humans. Our data to date show that the PDR is as sensitive as traditional methods of assessing hearing using subject feedback. A provisional patent filing protects the PDR methods, and the software and hardware that comprise the PDR system. To validate PDR as a diagnostic test, it must be shown to be as sensitive, and detect the same deficits, as the ABR in a clinical setting. Therefore, software, hardware, and methods will be optimized for use at in a clinical setting. PDR-based thresholds will be measured and compared to ABR thresholds in 80 infants, 3 - 18 mo, who were referred after newborn screening, or have at-risk factors for HL. To ensure the validity of the comparison, ABR and PDR thresholds will be measured in the same infant, on the same day, using similar sounds and by the same audiologist at the Doernbecher Children’s Hospital (OHSU). Data gathered will not only validate clinical application of the PDR, but will be the first systematic assessment of sound-elicited pupil responses in infants with or without HL. This data will enable us to seek further funding for develo...