HIGH-FREQUENCY DISTORTION PRODUCT OTOACOUSTIC EMISSIONS MEASURED BY TWO SYSTEMS: AN EXAMPLE OF A SUBJECT WITH NORMAL HEARING.

Background: Distortion product otoacoustic emissions (DPOAEs) are most commonly measured up to 6 kHz. However, there are now systems available that can measure DPOAEs up to 16 kHz. The purpose of this study was to compare two such systems. Case report: One subject with hearing thresholds below 20 dB HL at frequencies from 0.125 to 16 kHz was used to compare DPOAEs measured by the two systems. The HearID+DP (Mimosa Acoustics) and SmartDPOAE (Intelligent Hearing Systems) were used. DPOAEs were measured at frequencies from 0.5 to 16 kHz. Short-time repeatability was assessed by comparing DPOAE amplitudes between two measurements, with the second measurement made after refitting the probe. DPOAEs were above the noise for all tested frequencies. Comparison of results from the two systems showed that the differences between consecutive measurements and between the two systems was lowest in the 1-8 kHz range and highest in the 9-16 kHz range. However, even in the 1-8 kHz range, differences between response levels averaged 4 dB. Conclusions: Both systems provided DPOAE levels that were consistent with normal hearing thresholds. However, the differences between the two systems were quite high and may be too large to detect small changes in cochlear status if different equipment is used. [ABSTRACT FROM AUTHOR]