Exploring the Potential of Using the Integrated Digit-in-Noise Test as a Measure of Speech Recognition in Older...

This study aimed to explore the integrated digit-in-noise test (iDIN) as a tool for assessing speech recognition in noise among older hearing aid (HA) users, including those who cannot be tested using conventional sentence-in-noise tests.

The study involved 81 older HA users with moderate-to-severe hearing loss. Participants underwent the iDIN, along with two sentence-in-noise tests (Mandarin Hearing in Noise Test [MHINT] and Mandarin Chinese Matrix Sentence Test [CMNmatrix]) and two working memory (WM) tests (reading span test and digit span test). Correlation analysis and hierarchical multiple regression were employed to relate iDIN outcomes to conventional sentence-in-noise test results.

Among 56 participants who completed all tests, high correlations (ranging from .66 to .73) were observed between speech recognition thresholds (SRTs) measured using sentence-in-noise tests and SRTs measured with two-, three-, four-, and five-digit sequences on the iDIN. Reading span and two-digit SRT were significant predictors for SRTs measured using the CMNmatrix test. The two-digit SRT and the difference between five-digit and two-digit SRTs accounted for 57.9% and 61.3% of the variance in MHINT and CMNmatrix SRTs, respectively. When using 0.5 as the cutoffs for the two-digit SRT, among the 81 participants, the two-digit SRT (sensitivity: 0.818; specificity: 0.895) effectively differentiated those who could successfully complete sentence-in-noise tests.

The findings highlight the potential of the iDIN as a simple, quick, and reliable tool for measuring speech recognition that correlates well with performance on conventional sentence-in-noise tests and for those who could not be tested using these conventional measures. While results on short digit sequences primarily reflect auditory function, longer digit sequences involve the contribution of WM function, providing additional information regarding an individual's ability to understand speech in noise.