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To determine the influence of radixin on cochlear amplification and sensory cell function, we used a custom rapid confocal imaging technique to examine stereocilia motion while recording the electrical potentials produced by the sensory cells during acoustic stimulation. Little is known about this regulation, but we note that stereocilia may be capable of active force generation 9, 10, acting in concert with forces generated within the soma of outer hair cells 11, 12 to establish normal hearing sensitivity and frequency selectivity. Given radixin’s important role in the network of proteins within stereocilia, we hypothesized that radixin may contribute to the regulation of stereocilia function in the mature inner ear. While the functional relevance of these interactions has not been clarified, it is evident that phosphorylated radixin links the actin cytoskeleton with various transmembrane adhesion proteins, such as CD44 7, 8. Radixin is enriched within stereocilia 4, and bioinformatic analyses suggest that it is a hub in a network of interacting molecules 5 associated with the mechanotransduction process, such as phosphatidylinositol-4,5-bisphosphate (PIP 2), calmodulin, and calcium 6. From these observations, it is clear that radixin is necessary for normal hearing, but the physiological role of the protein remains obscure. The protein radixin appears to be an important component of this machinery, since radixin-deficient mice are deaf 1 from an early age and biallelic variants in the human RDX gene is a cause of non-syndromic neurosensory hearing loss (DFNB24 MIM #611022 2, 3. The sensory cells of the inner ear are equipped with stereocilia, which harbor the molecular machinery that permits sound to be converted into electrical potentials. We conclude radixin is necessary for ensuring normal conversion of sound to electrical signals in the inner ear. This may be overlooked by newborn hearing screening and explained by multiple disturbances in postnatal sensory cells. We identified patients with RDX variants with normal hearing at birth who showed rapidly deteriorating hearing during the first months of life. These unique functional alterations demonstrate radixin as necessary for conversion of sound into electrical signals at acoustic rates. Other functional measures, including electrically induced sensory cell motility and sound-evoked stereocilia deflections, showed a minor amplitude increase. Radixin inhibition decreased sound-evoked electrical potentials. To determine how radixin influences hearing sensitivity, we used a custom rapid imaging technique to visualize stereocilia motion while measuring electrical potential amplitudes during acoustic stimulation. Radixin is important for hearing but remains functionally obscure. The stereocilia of the inner ear sensory cells contain the actin-binding protein radixin, encoded by RDX.