The purpose of this research study is to determine if a medication along with a computer program designed to improve memory and other mental processes can help people like yourself with tinnitus. The medication that will be investigated, d-cycloserine, was developed as an antibiotic. However, more recently, research in other studies has shown that this medication may enhance learning and memory. The investigators would like to determine if computer programs designed to improve memory and attention are enhanced by this medication. In addition, the investigators hope to learn if the use of these programs can help participants with their tinnitus as well as their ability to remember and focus. All research participants will receive therapy with a computer-based program designed to improve memory and attention. Half of participants will also receive d-cycloserine while the other half of participants will receive placebo. The placebo is a sugar pill without active medication.

Tinnitus is the perception of a "ringing or hissing" sound in the absence of an acoustic stimulus affecting more than 40 million people in the United States. While the exact etiology of chronic bothersome tinnitus is unknown, current evidence based on numerous studies and neuroimaging results suggests chronic bothersome tinnitus involves the central nervous system with abnormalities in neural networks including attention and emotional networks. These neuroplastic changes in multiple neural networks may offer targets in the treatment of chronic bothersome tinnitus.

The Brain Fitness Program® (Posit Science Corporation, San Francisco, California) is a cognitive rehabilitation program that has been used in the treatment of schizophrenia and geriatric populations, and has been shown to have favorable results by reorganizing aberrant neural networks. Preliminary results from our team have shown improvements in tinnitus severity and cognitive functioning for participants with chronic bothersome tinnitus using this cognitive rehabilitation program.

Recent studies in numerous disorders have shown d-cycloserine (DCS) augments learning therapy programs by enhancing neuroplasticity. In addition, the adjuvant use of DCS with learning therapies has been found to accelerate symptom reduction decreasing the time-burden needed for learning therapies. Based on the belief that chronic bothersome tinnitus involves changes in malleable neural networks that can be targets of therapy and that DCS enhances neuroplasticity, the investigators hypothesize that adjuvant DCS with cognitive rehabilitation treatment may improve tinnitus severity and the cognitive deficits associated with chronic bothersome tinnitus.

This randomized-controlled trial will use an abbreviated cognitive rehabilitation program given for 5 weeks with DCS or placebo to evaluate the impact of a neuroplasticity-sensitizing drug on tinnitus symptom severity and cognitive performance among patients with chronic bothersome tinnitus. A positive result on this study will have numerous implications, including offering a new treatment option for chronic bothersome tinnitus with few known side effects and limited time commitment or cost.

Inclusion Criteria:

• Participants must be between the ages of 35 and 65.
• Participants must have subjective, unilateral or bilateral, non-pulsatile tinnitus for at least a duration of 6 consecutive months.
• Participants must have bothersome tinnitus as defined by a THI ≥ 30.
• Participants must have access to a computer for at least 60 minutes per day, 2 days per week, for five consecutive weeks.
• Participants must be willing to work on the Brain Fitness Program® that will be provided at least 60 minutes per day, 2 days per week, for 5 consecutive weeks.
• Participants must be willing to return for two treatment study visits during the first week after enrollment in the study and an additional study visit after 5 weeks.
• Participants must be willing to complete the Brain Fitness Program® and other assessments as prescribed.
• Participants must be able to read, write, and speak English fluently as the Brain Fitness Program, tinnitus assessments, and neurocognitive testing are written and administered in English.
• Women of child-bearing age must agree to use a study-approved form of contraception and agree to not try to become pregnant during the duration of the study. If a participant becomes pregnant, they should inform the PI and will be immediately withdrawn from the study.
• Participants must be able to provide valid informed consent.

Exclusion Criteria:

• Participants with a tinnitus diagnosis related to a Workman's Compensation Claim or any other litigation-related situation.
• Participants with tinnitus related to retrocochlear lesions, cochlear implants, or other unknown anatomic/structural lesions of the brain, skull base, temporal bone, or ear.
• Participants with hearing impairment such that they are unable to hear the highest volume of the computer cognitive training program.
• Participants with an active diagnosis of any acute or chronic central neurological condition including: Parkinson's disease, Multiple Sclerosis, Alzheimer's Disease, cerebral infarcts, traumatic brain injury, epilepsy, dementia, and/or a history of brain tumor(s).
• Subjects who have an active diagnosis of an anxiety disorder, psychosis or any psychiatric co-morbidity that may complicate the interpretation of study results.
• Participants with symptoms of severe depression on the Patient Health Questionnaire-9 (subjects who score >15 on the Patient Health Questionnaire-9 (PHQ-9) designed to screen for depression).
• Active alcohol and/or drug dependence or history of alcohol and/or drug dependence within the last year.
• Participants with kidney or liver impairment, a heart condition, porphyria, porphyria among family members, or an allergy to DCS.
• Participants who take any medication that is contraindicated with DCS.
• Use of any medications that may alter or affect cognition including, but not limited to, sedatives, hypnotics, narcotics, and opiates.
• Women who are pregnant or breast-feeding.
• People who have ever used the Brain Fitness Program® or any other computer based Brain Exercise or Brain Training programs within the prior year.
• Use of Neuromonics device for tinnitus treatment, or currently undergoing Tinnitus Retraining (TRT) program.
• Any condition the PI determines would render the study to not be in the best interest of the patient.