Figure 4. Other example of the effects of 15-min complete ischemia on a gerbil ear previously exposed to auditory fatigue. Primary levels: 70 dB SPL. Closed circles: initial DPgram; open circles: DPgram after auditory fatigue; open squares: after ischemia; thinner line: average noise floor. Beyond the thin vertical line, DPOAEs were more or less affected by auditory fatigue.