Recent advances in the field of the physiology of inner ear fluids permitted the characterization of the molecular mechanisms involved in critical processes such as the absorption of K⁺ through cochlear sensory hair cells (mechanoelectrical transduction) or the secretion of K⁺ by marginal cells of the stria vascularis. In addition, new pathways for ion circulations were evidenced. Mutations of transporters involved in some of these pathways, especially in K⁺ recycling through gap junction systems, and in local pH regulation, are among the most frequent etiologies of genetic deafness in humans.