Project summary This proposal is for the purchase of temporal bone histological tissue scanning equipment as a supplement to the parent proposal, R01 DC012262, entitled “Spectro-temporal interactions in electric and acoustic auditory perception”. The long-term goal of the parent proposal is to improve auditory and speech perception via cochlear implants (CIs) and hearing aids, through a greater understanding of the basic mechanisms that contribute to, and limit, the perception of speech in challenging acoustic conditions. The long-term goals of the parent project will benefit greatly from the use of otopathological specimens. Our university is fortunate to have one of the three largest human temporal bone laboratories in the US, housing a well-diversified collection of 2,252 human temporal bones. Our plan is to use digitized human temporal bone slides to relate the behavioral and neuroimaging results gathered under the parent grant with otopathological data, providing a unique opportunity to relate our perceptual findings to the cellular level within the inner ear and thereby assess the pathological underpinnings of altered speech perception. Our plan is to search the database of our otopathology laboratory and select specimens of special interest to our research (from patients who have similar background as ones in our clinical study: age- and sex- matched, with and without hearing loss). These specimens will be scanned using a high-resolution, high-throughput tissue scanner, which will be acquired through this funding opportunity (Zeiss Axioscan 7). We will then scrutinize the middle and inner ears of temporal bones for properties that relate to the perceptual performance of patients with CIs and hearing aids. We will perform quantitative analysis of cochlear hair cells, stria vascularis, spiral ganglion neurons, and dendritic distal cochlear nerve fibers. The benefits of having digital versions of the archival temporal bones will extend far beyond the parent project and beyond researchers at our institution, as these digital versions will protect the information from these irreplaceable specimens from being damaged in the case of accidents or natural disasters. In addition, by making the digitized collection of archival specimens widely available, they will become an invaluable long-term resource to the wider clinical and scientific communities involved with auditory and temporal bone research, meeting one of the fundamental objectives of the NIDCD Registry. The images will ultimately be made available to the scientific community through NIDCD approved databases.