Comparing the Results of Sound Field Audiometry With Traditional Headphone-Based Audiometry: Implications for Assessing Hearing Aid Benefits Using Functional Gain

Background and Objectives: This study aimed to compare sound field audiometry (SFA) and headphone-based audiometry (HPA) during the hearing aid fitting process. Factors associated with the differences between the two methods were also investigated. Subjects and Methods: We retrospectively reviewed 42 patients who underwent both unaided SFA and HPA on the same day. Results: Hearing thresholds obtained in SFA were lower than those measured with HPA at 250 Hz (p=0.016). No significant differences were observed at other frequencies. When comparing the clinical characteristics of the groups with lower and higher thresholds of SFA at 250 Hz, patients with mixed hearing loss (MHL) were more prevalent in the group with lower hearing thresholds in SFA, whereas those with sensorineural hearing loss (SNHL) were more common in the group with equal or higher thresholds in SFA (p=0.011). Moreover, in subjects with SNHL, no significant difference was observed between the average of the thresholds at the four frequencies (4-FA) of SFA and that of HPA (p=0.156), while a significant difference was observed in subjects with MHL (p=0.028). When compared across the frequency, the thresholds of SFA at 250 Hz and 1,000 Hz were significantly lower than those of HPA (p=0.004 and p=0.009, respectively) in MHL. Conclusions: Improvement in aided hearing in SFA compared with unaided HPA must be interpreted with caution at lower frequencies in subjects with MHL. Meanwhile, when validating the efficacy in HA users with SNHL, the process can be simplified using unaided HPA instead of SFA; however, unaided SFA should be employed in those with MHL.