Improving the efficiency of the digit triplet test using digit scoring with variable adaptive step sizes

Objective: To investigate modifications of the Flemish Digit Triplet Test (DTT) to improve its efficiency, i.e. the use of a low-pass filtered noise and variable adaptive step sizes according to a digit scoring procedure, targeting different recognition probabilities.

Design and study sample: Speech reception thresholds (SRT) were evaluated in terms of their test-retest reliability and correlation with pure tone averages (PTA) in a group of 68 adult participants with different degrees of hearing impairment.

Results: The use of a low-pass filtered noise did not result in better test-retest reliability or an improved SRT-PTA correlation. Using digit scoring with adaptive step sizes parametrised to target a recognition probability of 79% (D79), corresponding to the recognition probability of the currently used DTT with triplet scoring and fixed adaptive step sizes of 2 dB, increased test-retest reliability. Lower recognition probabilities of 57 and 35% demonstrated worse reliability and worse SRT-PTA correlations.

Conclusions: Given the increased test-retest reliability of D79, a similar reliability as for the currently used DTT could be obtained after considerably fewer trials, leading to a profit in test duration.