PP109 - Digits-in-Noise Test for Assessing Performance in Bone Conduction Hearing Aid Users

Abstract: This study examined the utility of the Digits-in-Noise (DIN) test for assessing benefit in bone conduction hearing aid (BCHA) users. Twenty individuals with conductive or mixed hearing loss (mean age 25.5 years) completed the DIN and the HINT-Brazil in unaided and aided conditions. Both tests used adaptive procedures to estimate SRTs. Significant improvements from unaided to aided conditions were observed for the HINT (5.97 to –0.97 dB SNR) and DIN (12.8 to –6.50 dB SNR). Moderate correlations were found between tests. Findings indicate that the DIN is sensitive to aided benefit and may serve as an efficient clinical alternative.

Summary: Rationale: Bone conduction hearing aids (BCHAs) require sensitive outcome measures to assess rehabilitation benefit. Speech-in-noise tests are essential for capturing functional performance beyond pure-tone thresholds, yet Brazilian Portuguese lacks validated, fast, and clinically accessible options. The Digits-in-Noise (DIN) test provides a reliable and ecologically valid measure of auditory function and is increasingly used to assess hearing devices' benefit. However, data on the performance of BCHA users on sound-field DIN testing remain limited.

Objective: This study aimed to characterize the performance of bone conduction hearing aid users on the DIN test, comparing it with a gold-standard measure.

Methods: This cross-sectional study (ethics approval: 7.673.982) included 20 individuals aged 12 to 41 years (mean: 25.5 ± 9.86), with bilateral conductive (n=15) and mixed (n=5) hearing loss, of varying degrees: moderately severe (n=13), severe (n = 6) and profound (n = 1). All participants were unilateral users of the BAHA 6 Max (Cochlear Corporation), with percutaneous (n=11) and transcutaneous (n=9) systems. The sample size was considered adequate (n=20; powerr >85%). The DIN and HINT Brasil (gold standard) were conducted in a soundbooth, in counterbalanced order, under unaided and aided conditions. Speech and noise stimuli were presented via loudspeaker order of presentation positioned at 0° azimuth and 1 meter from the participant. Both tests use adaptive procedures in which the signal-to-noise ratio (SNR) is varied across trials to estimate the speech reception threshold (SRT). Statistical analyses included paired t-tests or Wilcoxon tests, depending on data distribution, and Spearman correlation.

Results: Mean SRTs significantly improved from the unaided to the aided condition in both tests: from 5.97 to –0.97 dB SNR for the HINT (t = –9.04, p < .001) and from 12.8 to –6.50 dB SNR for the DIN (W = 1.00, p < .001). Positive correlations were observed between the HINT and DIN in the unaided (r = 0.509; p = 0.044) and aided conditions (r = 0.396; p = 0.103), although the latter was not statistically significant.

Conclusion: The DIN was sensitive in detecting improvement between unaided and aided conditions. The moderate correlations between the two tests indicate that the DIN may serve as a time-efficient alternative for assessing functional benefit in BCHA users. Further research should establish normative data for BCHA users, and explore the DIN’s responsiveness to clinical interventions, supporting broader clinical implementation.