High-frequency (8–20 kHz) reference thresholds for audiometry

Abstract

ANSI (S3.6-1996) and ISO (CD 389-5, 1996) have reported interim high-frequency (8–16 kHz) reference equivalent threshold sound pressure levels (RETSPLs). Since the interim RETSPLs were derived using very limited data, there is a need to increase the data base for specifying high-frequency RETSPLs. Thus, this study determined high-frequency (8–20 kHz) thresholds for 50 young adults having normal low-frequency (0.25–8 kHz) hearing across four test sessions, separated by at least one day, using Sennheiser HDA 200 and Koss HV/Pro earphones. The mean thresholds increased as frequency increased, especially at 16 kHz and above, and were similar to the ANSI and ISO interim RETSPLs. However, the standard deviations were very high and the range scores were very wide for each earphone at each frequency. This would indicate that specifying high-frequency RETSPLs may not be feasible due to very high intersubject threshold variability. On the other hand, the intrasubject threshold differences across each possible test session comparison were found to be very repeatable and within a clinically acceptable range. This would indicate the usefulness of high-frequency audiometry for monitoring patients having or suspected of having otopathology. [Work supported by the Pennsylvania Lions Hearing Research Foundation.]