Disentangling the Contributions of Extended High-Frequency Thresholds and Chronological Age to TEOAE Amplitudes: A Hierarchical Regression Analysis

Objective: Extended high-frequency (EHF) audiometry (9–20 kHz) is increasingly recognized as a sensitive tool for detecting early cochlear damage. However, the extent to which EHF sensitivity influences cochlear active mechanisms in the lower frequencies, measured by transient evoked otoacoustic emission (TEOAEs), remains controversial due to the confounding effect of aging. The primary aim of this study is to disentangle the contributions of chronological age and EHF-thresholds to TEOAE amplitudes in adults with normal hearing.Materials and Methods: This study was conducted on 160 adults with normal conventional hearing (0.125-8 kHz frequency thresholds ≤20 dB HL ). Participants underwent standard and EHF-audiometry, followed by TEOAE recording. Averaging responses at 1, 1.5, 2, 3, and 4 kHz yielded the TEOAE. Relationships between variables were analyzed using Pearson correlations and a three-step hierarchical multiple regression analysis.Results: Age correlated moderately with TEOAE amplitudes (r=-.39, p<.001), but EHF thresholds showed no significant association (r=-.08, p=0.40). In the hierarchical model, age accounted for 15% of the variance (R²=.149, p<.001), while the addition of EHF thresholds did not account for a statistically significant amount of additional variance (ΔR²<.001, p=.70) when age and standard sensitivity were controlled.Conclusions: In adults with normal conventional hearing, TEOAE amplitude decline is primarily associated with age-related cochlear changes rather than EHF sensitivity. When age is statistically controlled in normal-hearing adults, basal cochlear thresholds provide limited additional unique variance for low-frequency emission amplitudes.