Audibility primarily drives the relationship of digits-in-noise recognition with hearing loss and age

To examine how audibility affects digits-in-noise (DIN) recognition, and how age and hearing loss influence recognition after audibility compensation.

Pure-tone thresholds and speech perception thresholds (SRTs) were measured. The SRTs were obtained using a DIN-test at 70 dB SPL noise-level with the standard speech/noise spectrum (DIN₇₀) and at individually adjusted speech levels with a high-frequency tilted spectrum (DIN_var) to optimise audibility. The speech intelligibility index (SII) was used to correct for audibility effects in the DIN₇₀ test.

1575 older adults from the population-based Rotterdam Study with mild-to-moderate hearing loss, of which 713 participants had a DIN_var measurement. This subgroup had significantly better hearing thresholds.

With the DIN₇₀ test, significant associations with age (ζ = 0.11) and the pure-tone average (PTA) (ζ = 0.32) were found for the entire population. After SII-modelling, these were substantially reduced (age: ζ = 0.06, and PTA: ζ = 0.08). The SRT of the DIN_var test also revealed weak relationships with age (ζ = 0.04) and PTA (ζ = 0.05).

Audibility is the primary determinant of digit triplets-in-noise recognition in older adults with mild to moderate age-related hearing loss. After compensation of audibility, there is hardly any effect of supra-threshold deficits related to age and PTA.