Associations of standard and extended high-frequency thresholds with suprathreshold auditory brainstem response morphology in normal-hearing adults

The Auditory Brainstem Response (ABR) is essential for assessing neural integrity, yet the influence of subclinical extended high-frequency (EHF) deficits on waveform morphology remains insufficiently characterized. This cross-sectional study evaluated the distinct predictive utility of Global Standard Averages (0.125–8 kHz) versus EHF thresholds (9–20 kHz) for ABR latencies and amplitudes in 89 otologically healthy adults. While all but one participants exhibited clinically normal hearing thresholds (≤20 dB HL) across standard frequencies, multiple linear regression analyses were employed to identify independent predictors of neural synchrony and transmission timing, controlling for age and sex. Results indicated a functional dissociation between peripheral magnitude and central timing predictors. Even after adjustment for covariates, EHF averages remained a significant independent predictor of Wave I amplitude (β = -0.28, p = .015), underscoring the critical link between basal cochlear status and distal neural synchrony. Conversely, Wave V latency was primarily predicted by biological sex (β = -0.30, p = .006) and standard high-frequency sensitivity (4–8 kHz) rather than ultra-high frequencies. Additionally, analyses of the Wave V/I amplitude ratio did not demonstrate expected age-related central gain, likely due to the cohort's preserved peripheral integrity. Collectively, these findings suggest that EHF sensitivity serves as a superior marker for distal auditory nerve integrity compared to standard measures. Consequently, incorporating EHF audiometry into diagnostic protocols offers enhanced sensitivity for detecting subclinical cochlear deficits that evade capture by standard audiometric batteries.