The Core Outcome Measures in Tinnitus (COMiT) initiative has recommended a minimum standard of five outcomes when designing a clinical trial to assess the efficacy of sound-based interventions. These are: ability to ignore, concentration, quality of sleep, sense of control and tinnitus intrusiveness. The next stage is to consider what measurement instruments might be appropriate for assessing these constructs. The current study aimed to systematically gather existing instruments used to assess concentration. A total of 6240 potentially relevant records were identified. Duplicates and non-published works were removed, leaving a total of 3599 records. A procedure was developed to sample a subset of records, in order to identify relevant instruments without exhaustively reading all 3599 texts. Initially 559 records were identified by screening 1000 articles; 500 of which were randomly selected, and 500 were the most recent publications identified from the PubMed database. Using predefined criteria for data saturation, information about measures of concentration was extracted from the 559 full texts. However, data saturation was reached by 240. Thirteen candidate instruments were identified. The next step will be to assess content validity and feasibility of administration for all these candidate instruments. Findings will inform future recommendations for how to measure concentration in clinical trials to ensure results of trials can be easily compared, contrasted, and synthesized.