The Generation Mechanisms and Repeatability of 2F1 - F2 Distortion Product Otoacoustic Emissions: study on normally hearing subjects

The 2F1-F2 distortion product otoacoustic emission (DPOAE) is considered to consist of two generation mechanisms, the so-called place-fixed and wave-fixed mechanisms, depending on the frequency ratio F2/F1. The general assumption is that for a small frequency ratio there is a predominantly place-fixed emission mechanism, while with a larger frequency ratio there is a predominantly wave-fixed mechanism. There is also a lack of published data on the repeatability of the two components when separated. One aim of this study was therefore to identify the wave-fixed and place-fixed components of the 2F1-F2 DPOAE using a time-window separation method. The second aim was to quantify the test-retest repeatability of the separated 2F1-F2 DPOAE components in a group of normally hearing subjects. Results confirmed the presence of wave-fixed and place-fixed components for 2F1-F2 and a predominance of place or wave-fixed DPOAE as a function of frequency ratio. This pattern varied somewhat among subjects. Moreover, regardless of which component was stronger for any F2/F1, both components were highly repeatable across time within individual ears