Fig. 3.

Amplitude modulation of EEOAE waveforms (2024 Hz, 10 mA electrical stimulus) with increasing levels of an 86 Hz tone as indicated in dB SPL. The scala media CM is shown as recorded and as its inverted mirror image (bottom left panel). Negative polarity of the scala media CM corresponds to basilar membrane displacement to scala vestibuli (SV) and positive polarity to scala tympani (ST). CM was shifted in phase by −430 μsec to compensate for the travel time of EEOAE from its generation site in the second turn to the recording microphone, and scaled and offset to fit as closely as possible to the modulation envelope of the EEOAE waveform. Scaling factors and offset were constant over the intensity range.