High-frequency thresholds using a quasi-free-field technique

A free-field transducer system for high-frequency audiometry was applied on two groups of otologically normal, non noise-exposed subjects tested at the frequencies 4--8--10--12--14--16--18--20 kHz. The former group consisted of 46 children 10--12 years old and the second group of 40 adults aged 18--24 years. All participants in the youngest group were able to hear 20 kHz and no difference between right and left ear or between sex could be shown. A similar result was found in the adult group except that 4 males were unable to hear 20 kHz. Hearing thresholds for the two groups were almost identical at 8--14 kHz. Above this frequency range the youngest group showed a statistically significant lower threshold at 18 and 20 kHz. This group might be used for a zero-dB hearing threshold level in further high-frequency studies. The advantage of transferring the SPL value from the entrance to ear canal to absolute ear drum pressure level is discussed.