Functional outcomes of conventional air- and bone-conduction hearing aids in patients with unilateral sensorineural hearing loss.

Abstract

Purpose: To explore speech performance in multi-talker environments, subjective satisfaction with hearing and spatial ability, and factors influencing outcomes in patients with unilateral sensorineural hearing loss (USNHL) fitted with conventional hearing aids (HAs).

Methods: A total of 32 native Mandarin-speaking individuals with USNHL were retrospectively enrolled. Patients were fitted with either air-conduction (AC) or bone-conduction (BC) HAs based on individual suitability. Real-ear measurements (REM) were performed for AC HA fitting according to NAL-NL2 (adults) or DSL v5 (pediatric) prescriptive targets. At the initial fitting session, speech perception in noise was assessed under multi-talker conditions across three spatial configurations representing binaural squelch, summation, and head shadow effects. The Chinese version of the Speech, Spatial and Qualities of Hearing Scale (C-SSQ12) was administered to evaluate subjective performance. Follow-up assessments at 6 months included speech perception testing, re-administration of the C-SSQ12, and an overall satisfaction survey.

Results: Comparing aided and unaided conditions at the initial HA fitting, no significant differences in speech recognition threshold (SRT) were observed under S₀N₀, S₀N_SSD, or S_SSDN_NH configurations (p = 0.5983,p = 0.1008, p = 0.9375, respectively). At 6-month follow-up (n = 12), no significant improvements in speech perception were detected compared to baseline (p > 0.05 for all configurations). However, regarding C-SSQ12 outcomes (n = 26), scores for questions assessing spatial localization (Questions 6 and 7) showed significant improvements at 6 months compared to baseline (r=-0.5691, p = 0.004 and r=-0.6674, p < 0.001, respectively), while the score for music perception (Question 10) declined (r=-0.5254, p = 0.007). The effect sizes were all large according to Cohen's standards. At initial fitting, a negative correlation was observed between hearing loss duration and SRT variation under S_SSDN_NH (r =-0.3549, p = 0.0463), and a negative correlation was found between worse ear pure-tone average (PTA) and ∆SRT under S₀N_SSD (r=-0.4057, p = 0.0212). Pre-aided speech was correlated negatively with ΔSRTs under all three conditions (p all < 0.05). The worse ear PTA was positively correlated with improvement in total C-SSQ12 score at 6 months (r = 0.4743, p = 0.0144).

Conclusion: Within a 6-month adaptation period, patients with USNHL fitted with conventional HAs demonstrated limited improvements in only two items of subjective spatial perception abilities, while the majority of subjective domains and all objective measures of binaural speech-in-noise performance showed no significant benefit. Hearing loss duration, pre-aided speech, and worse ear PTA emerged as factors influencing short-term speech outcomes at initial HA fitting. The worse ear PTA also influenced subjective speech, spatial, and qualities of hearing performance at 6-month follow-up.