[A preliminary comparison of 2-digit and 3-digit digit-in-noise tests in hearing screening]

Objective: This study aims to preliminarily explore the impact of cognitive function on 2-digit and 3-digit digit-in-noise tests in the Ningbo dialect version, particularly when used for hearing screening. Methods: A total of 31 older native speakers of the Ningbo dialect were selected. The cohort comprised 13 males and 18 females, with an age range of 60 to 88 years and a mean age of 73.6 years. Participants completed pure-tone audiometry, the Ningbo dialect versions of the 2-digit and 3-digit digit-in-noise tests twice, the Chinese version of the Montreal Cognitive Assessment (MoCA-BC) basic scale, and the auditory version of the digit span test. Results: Spearman's correlation analysis showed that MoCA-BC scores were significantly correlated only with the second SRT (speech reception threshold) of the digit triplet test. There was no significant correlation between digit span scores and the results of any of the digit-in-noise tests. Attention scores from the MoCA-BC were significantly correlated with the first (rs=-0.374, P=0.038) and second (rs=-0.369, P=0.041) SRTs of the 3-digit condition but showed no significant correlation with the first and second SRTs of the 2-digit condition. The effectiveness of the 3-digit and 2-digit in hearing screening was found to be generally consistent. When using an average hearing threshold of 35 dB HL in the better ear as the hearing screening cut-off point, ROC curve analysis revealed that the areas under the curve (AUC) for the first and second trials of the 2-digit and the first and second trials of the 3-digit test were 0.868, 0.864, 0.873, and 0.857, respectively. Conclusion: Cognitive function has little effect on the results of 2-digit and 3-digit digit-in-noise tests. However, compared to the 3-digit, the 2-digit is simpler and less affected by cognitive decline.