The purpose of this study is to determine whether prednisone, methotrexate, and cyclophosphamide are effective in the treatment of rapidly progressive sensorineural hearing loss in both ears. This condition is called autoimmune inner ear disease (AIED), because it is thought that the hearing loss is triggered by an autoimmune process. Treatment attempts to suppress or control this process with powerful anti-inflammatory drugs. This is a Phase III, outpatient study. All study participants will be assigned to one of four different groups testing the experimental use of drugs. The study is scheduled to run for 18 months, with a minimum of 11 visits per participant.