Efficacy of the Digit-in-Noise Test: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES: Although the digit-in-noise (DIN) test is simple and quick, little is known about its key factors. This study explored the considerable components of the DIN test through a systematic review and meta-analysis. MATERIALS AND METHODS: After six electronic journal databases were screened, 14 studies were selected. For the meta-analysis, standardized mean difference was used to calculate effect sizes and 95% confidence intervals. RESULTS: The overall result of the meta-analysis showed an effect size of 2.224. In a subgroup analysis, the patient’s hearing status was found to have the highest effect size, meaning that the DIN test was significantly sensitive to screen for hearing loss. In terms of the length of the presenting digits, triple digits had lower speech recognition thresholds (SRTs) than single or pairs of digits. Among the types of background noise, speech-spectrum noise provided lower SRTs than multi-talker babbling. Regarding language variance, the DIN test showed better performance in the patient’s native language(s) than in other languages. CONCLUSIONS: When uniformly developed and well validated, the DIN test can be a universal tool for hearing screening.