The digit triplet test: a scoping review.

Objective: This review article presents an overview of all Digit Triplet Tests (DTT) and digits-in-noise tests (DIN) and their variations in language, speech material, masking noise, test procedures, and targeted population. The effects on aspects of validity, reliability, and feasibility are investigated.
Design: Scoping review.
Study Sample: All studies referring to the DTT and DIN were collected from Pubmed and Embase. Search terms "digit triplet test" and "digits in noise" were used. Citations of selected articles were scanned backwards in time (the bibliography of the already selected research article) and forward in time (articles that cited the already selected research article). The search terms yielded 95 results in total. Eventually, 39 papers were selected.
Results: Analyses showed psychometric reference-curves with steep slopes and speech reception thresholds with high measurement precision which are strongly associated with pure tone audiometry. High sensitivity and specificity to detect elevated pure tone thresholds were noted for test variants. Certain procedural modifications of the DTT and DIN can further improve the test. Additionally, large-scale application of the DTT and DIN is feasible.
Conclusion: The DTT and DIN are a very valuable tool for screening and diagnostics for a wide variety of populations.