Extended high-frequency audiometry. Air- and bone-conduction thresholds, age and gender variations.

Air-conduction and bone-conduction thresholds have both been determined in the conventional audiometric frequency ranges and in the extended high frequencies through respectively 18 and 16 kHz for otologically healthy subjects in different age groups covering the age span 8-14 years through the eighth decade. Subjects younger than 30 years had conventional frequency air-conduction thresholds < or = 10 dB HL, whereas the corresponding thresholds of older subjects were within 0.1 and 0.9 percentiles of ISO 7029 (1984). Age- and gender-specific thresholds, medians and ranges, are presented for bone conduction in the extended high frequencies. Thresholds increase with both age and frequency in the range 8-16 kHz, and there is a largely non-significant tendency for thresholds to be higher in males. Threshold deterioration at the highest frequencies is already present at age 18-24 years compared with the youngest (8-14 year) age group.