Figure 3. (A) post- vs. pre-exposure DPgrams in a gerbil ear. Pre-exposure, 70 dB SPL: open circles ; 60 dB SPL, closed circles. Post-exposure, 70 dB SPL: thin dashed lines; 60 dB SPL, crosses. Thinner lines: average noise floor. (B) DPgrams of the same ear, 15 min after complete ischemia following auditory fatigue (70 dB SPL: open circles; 60 dB SPL: closed circles). The thinner vertical lines mark the limits of the interval where DPOAEs elicited by 60-dB-SPL primaries no longer differed from noise floor.