Research in the Hearing Research Center (HRC) combines theoretical and experimental studies of auditory processing to understand hearing in both normal and impaired auditory systems. Empirical studies include anatomical studies of the cochlea and brainstem, measurements of mechanical properties of cochlear structures, single-unit and multi-unit recordings in the cochlear nucleus and auditory cortex, and measurements of auditory evoked potentials and otoacoustic emissions, as well as measurements of hearing abilities of human listeners with and without hearing impairments. Theoretical studies, which are closely coupled to the empirical studies, include mathematical modeling of cochlear mechanics, single neurons, networks of neurons, and human performance.