Extended high-frequency thresholds in older adults

Most measures of auditory sensitivity at extended high frequencies (frequencies greater than 8 kHz) have been obtained from listeners with normal hearing less than 40 years of age. The purpose of this study was (a) to measure thresholds at frequencies above 8 kHz in older listeners who, as a group, have elevated thresholds at lower frequencies, and (b) to assess test-retest: reliability, age and gender effects, and the influence of thresholds below 8 kHz. Extended high-frequency (EHF) thresholds were measured for 162 older listeners 160-79 years) using a commercially available high-frequency audiometer, with a frequency range of 8 to 18 kHz and an intensity range of 0 to 110 dB SPL. Thresholds were measured once at the beginning of a 1 - to 2-hour test session and then remeasured at the end of the test session. EHF thresholds of older listeners with normal hearing at conventional audiometric frequencies were substantially higher than the thresholds reported for younger listeners with normal hearing by Dreschler and van der Hulst (1987). EHF thresholds of older listeners with hearing loss al conventional audiometric frequencies were further elevated as compared to older listeners with normal hearing. Differences in EHF thresholds between females and males were either not present or were reduced when gender differences in conventional audiometric thresholds were taken into account. No significant differences were seen in thresholds at 8 kHz and higher between the 60- to 69- and 70- to 79-year-old age groups. Results also indicated that thresholds above 8 kHz can be measured in older listeners within a clinically acceptable +/-10 dB test-retest range.