Mutations in ATP6V0A4, which encodes a subunit of the H+-ATPase proton pump, underlie distal renal tubular acidosis (dRTA), a condition that often involves deafness in addition to kidney-related problems. Lorente-Cánovas et al. now examine the auditory system in Atp6v0a4 knockout mice, which recapitulate the human renal dRTA phenotype and have impaired hearing. They report that the endolymphatic compartments in these mice are expanded, whereas hair cell development in the cochlea (which is crucial for normal hearing) is unaffected. Notably, Atp6v0a4 knockout mice lack an endocochlear potential (the voltage that is needed to make hair cells more sensitive to sound), although the K+ channels that normally help to generate this potential are strongly expressed. Together, these results establish Atp6v0a4 knockout mice as a model for dRTA-associated hearing loss. Page 434