Effect of dome size selection on speech discrimination in noise and localization abilities

Domes are favored in hearing aid (HA) applications due to their quick application, no need for ear impressions, and comfortable fit. However, there is limited understanding of how different dome types affect speech understanding in noise and localization abilities. This study aimed to investigate the effects of various dome types on these skills.The research involved 22 participants aged 35 to 59 (mean age 51.68 ± 7.04), consisting of 10 women and 12 men. All participants had mild to moderate bilateral sensorineural hearing loss and no prior experience with HA. The HA were adjusted using REM for three types of domes: open, power, and dual-vent. Speech understanding in noise was assessed with the HINT test, repeated across all dome types. For localization testing, eight speakers were positioned at 45° angles to present speech stimuli. Each speaker delivered two recordings, allowing for calculation of accuracy scores. Results showed no significant differences in HINT scores between quiet and noisy conditions for the three types of domes (p>0.05). However, when comparing noisy conditions, significant differences were found for open and power domes (NL-NR, NL-NF, p<0.001), and for dual-vent domes (NL-NF, NR-NF, p<0.001). Localization tests revealed no significant differences across dome types (p>0.05), but directional advantages, showed significant distinctions among the domes. When comparing directional advantages, the open dome showed differences at 135°-90°, double-vented dome at 135°-90°, 270°-135°, 315°-270°, power dome at 90°-45°, 270°-45°, 135°-90°, 270°-135° (p < 0.002). In conclusion, the study indicates that different domes respond differently when noise and stimuli come from various directions. Open and power domes produced similar results in speech perception, while the dual-vent dome exhibited notable differences. In localization, the open dome performed best, followed by the dual-vent and power domes. Selecting the most comfortable and suitable dome type is believed to enhance HA usage.