The purpose of this study is to evaluate the safety, tolerability, and exploratory efficacy of OTO-413 administered as an intratympanic injection for the treatment of speech-in-noise hearing impairment.

Inclusion Criteria:

• Subject has audiometrically-defined normal hearing or up to moderately severe hearing impairment.
• Subject has self-reported difficulty hearing in noisy environments for at least 6 months prior to Screening.
• Subject exhibited a speech-in-noise hearing deficit in at least one ear.

Exclusion Criteria:

• Subject is pregnant or lactating.
• Subject has the following hearing disorders or any other hearing disorders that may impact the efficacy assessments or safety of the subject in the opinion of the Investigator: Meniere's disease, congenital hearing loss, or genetic sensorineural hearing loss.
• Subject has a cochlear implant or consistently uses a hearing aid.
• Subject has worked at least 5 years as a professional musician or has had at least 15 years of formal musical training.
• Subject self-reports bothersome, subjective tinnitus and is consistently aware of their tinnitus throughout much of the waking day.