Evaluation of the Korean digits-in-noise test to classify the degree of hearing loss

To assess the feasibility of a newly developed PC-based Korean digits-in-noise (K-DiN) test for categorising the degree of hearing loss in participants with normal hearing and various degrees of hearing loss.

The results of the Korean matrix sentence test (K-matrix) were compared with the corresponding K-DiN test results. Correlation analysis examined the relationships between the K-DiN speech reception thresholds (SRTs), age, pure-tone average (PTA), and K-Matrix SRTs. Receiver operating characteristic curves were constructed to evaluate the discriminatory ability of K-DiN across different degrees of hearing loss.

K-DiN testing was conducted on 73 individuals with normal hearing and 166 individuals with hearing loss. Subsequently, 93 individuals were subjected to the K-Matrix.

The K-DiN SRTs exhibited significant correlations with the PTA thresholds and K-Matrix SRTs. For detecting mild hearing loss, the K-DiN test demonstrated 90% sensitivity and 98% specificity with a -4 dB signal-to-noise ratio cut-off, accompanied by an area under the curve (AUC) of 0.98. Furthermore, the more severe the hearing loss, the lower the AUC value.

The findings from this study highlight the K-DiN test's excellent discriminative ability for differentiating normal hearing from hearing loss and for categorising individuals into distinct hearing-loss groups.