Effects of the Conductive Component of Hearing Loss on Speech Discrimination Ability

OBJECTIVES: Effects of decreasing auditory activity on speech discrimination ability are not fully understood. To investigate influence of decrease in auditory activity due to conductive and sensorineural components of hearing loss (HL) on speech discrimination ability. MATERIALS AND METHODS: We retrospectively reviewed medical records of patients with suspected HL at Kitasato University Hospital in 2017 and 2018. Patients were divided according to pure-tone audiometry findings: no HL (N-HL), conductive HL (C-HL), sensorineural HL (S-HL), and mixed HL (M-HL) groups. RESULTS: In total, 149 patients (224 ears) were eligible. The maximum speech discrimination score (SDSmax) for all ears significantly negatively correlated with age (r = −0.29, p<0.0001) and bone conduction (BC) threshold (r = −0.55, p<0.0001). For patients aged <50 years in N-HL and C-HL groups, SDSmax was nearly 100%, with no significant difference. SDSmax was significantly lower for older patients (≥50 years) in the M-HL group than in the S-HL group, even though there were no significant differences in age and BC thresholds between groups. CONCLUSION: Decrease of auditory activity due to the conductive component of M-HL may worsen speech discrimination ability. Early treatment of M-HL would be desirable for the preservation of auditory function.