Abstract: Disclosed herein is a method of delivering a mutated tyrosine adeno-associated viral vector or a pharmaceutically active agent to an inner ear. The method comprises contacting the round window membrane with the vector or the pharmaceutically active agent, in which the permeability of the round window membrane having been enhanced to allow transport of the vector or the pharmaceutically active agent across it so as to deliver the vector or the pharmaceutically active agent to the inner ear. Also disclosed are methods to prevent or treat hearing loss and impaired balance in human subjects using the delivery method.