Speech discrimination and binaural processing in bilateral symmetric vs. asymmetric sensorineural hearing loss.

Abstract

Purpose: To investigate the effects of symmetric and asymmetric sensorineural hearing loss (SSNHL and ASNHL) on speech discrimination abilities and binaural processing, including integration and interaction.

Materials and methods: This cross-sectional study included 36 adult patients with bilateral sensorineural hearing loss, divided into two groups based on the symmetry of their hearing loss: ASNHL and SSNHL. Speech discrimination abilities were evaluated using the maximum speech discrimination score (SDSmax) with Arabic monosyllabic words. Binaural integration was assessed using the free-recall double dichotic digit test (DDT), while binaural interaction was evaluated through the binaural fusion test (BFT).

Results: The SDSmax of the worse-hearing ear in ASNHL patients (48.89 ± 10.13%) was significantly lower than in SSNHL patients (69.33 ± 7.97%) with comparable degrees of hearing loss. ASNHL patients exhibited a greater disparity between the better and worse-hearing ears in DDT scores (53.15 ± 13.98%) compared to SSNHL patients (22.96 ± 5.93%). Additionally, the BFT scores in ASNHL patients (55.14 ± 13.30%) were significantly lower than in SSNHL patients (72.92 ± 12.55%).

Conclusions: ASNHL patients experience greater impairments in speech discrimination, binaural integration, and interaction compared to SSNHL patients. These differences likely stem from auditory deprivation and asymmetry-induced deficits. Developing tailored hearing rehabilitation strategies is critical to addressing the unique challenges posed by asymmetric hearing loss.