Normative Extended High Frequency Audiometry in Young, Middle, and Older Populations

Objectives: Elevated thresholds in the extended high frequency hearing range have been associated with functional hearing deficits, such as speech-in-noise performance. However, unlike the standard frequency range, there are a lack of recommendations from organizations such as the International Standards Organization (ISO) and World Health Organization (WHO) regarding normative data in the extended high frequencies limiting clinical implications of this data. In the present study, we report proposed normative data in the extended high frequency region in over 726 participants evaluated on typical clinical equipment using methodology from both the ISO and WHO. We hypothesize that extended high frequency will worsen with age and show excellent test-retest reliability. Design: Audiometric thresholds were collected from 726 adult participants at all measurable frequencies between .25 and 16 kHz. Data were analyzed using the equations reported by the 2017 ISO 7029 report and by calculating a 4-frequency extended high frequency pure tone average in alignment with the WHO. Results: Males had worse hearing than females when analyzed using a 4-frequency PTA, but there was no significant difference in the age-related rate of decline. Extended high frequency thresholds (N = 129) showed excellent test-retest reliability (ICC > 0.9, p < 0.001). Extended high frequency 4-frequency PTAs in participants with normal hearing in the standard frequency range had a range of -11.25 to 92.5 dB.Conclusions: Adaptation of norms in the extended high frequency range is feasible due to agreement among the literature and stability of test-retest measurements. Male extended high frequency thresholds are worse than women, but the rate at which hearing declines does not differ between sexes. Future research in this area should take into account normative data and functional hearing performance.