Disequilibrium between acid and base in the inner ear was suggested to be an important factor leading to hearing impairment associated with SLC26A4 mutations. For acid-base homeostasis in the inner ear, gastric-type proton pumps might demonstrate antagonistic effects to pendrin, the protein encoded by SLC26A4. To investigate whether proton pump inhibitors might prevent or treat acute fluctuating hearing loss related to SLC26A4 mutations, we launch the current double-blind randomized clinical trial.