Fig. 7.

Steady-state amplitude of distortion product otoacoustic emissions (DPOAE) was unchanged by MPTP treatment. Steady-state DPOAE amplitude is a measure of the integrity of the outer hair cell population. DPOAE steady-state amplitude is depicted after opening the bulla (“Pre”), 30 min after applying artificial perilymph to the round window membrane, and 30 min after applying 50 mM MPTP to the round window membrane. The levels of F1 and F2 were systematically varied such that F2 was always 10 dB quieter than F1. DPOAE frequencies were 5.8 kHz (A), 8.7 kHz (B), and 11.7 kHz (C).