RecruitingGenetic interventionA Study of DB-OTO, an Adeno-Associated Virus (AAV) Based Gene Therapy, in Children/Infants, Adolescents and Adults With Hearing Loss Due to Otoferlin MutationsRegeneron is conducting a study of an investigational new drug called DB-OTO. DB-OTO is a gene therapy that is being developed to treat pediatric and adult participants who have severe-to profound and profound hearing loss due to changes in the otoferlin gene. The purpose of this study is to: * Learn about the safety of DB-OTO * Determine how well DB-OTO is tolerated (does not cause ongoing discomfort) * Evaluate the efficacy of DB-OTO (how well DB-OTO works)