Additional Study Information: This research study is investigating ketamine as a possible treatment for tinnitus or ringing in the ears. Ketamine is FDA approved for anesthesia and depression that doesn't respond to regular antidepressants. It is not approved for tinnitus. This study involves two scans using magnetic resonance imaging (MRI). Each of the scans last one and a half hours each. Ketamine is administered during one of the scans. The study also involves three audiological appointments, each lasting one hour, to measure tinnitus symptoms. Compensation for time and travel are provided. Contact (646) 774 7654 for more information.