FIG. 2.

Anesthesia suppressed the magnitude of the average DPOAE-adaptation index measured in alert rabbits. Shaded regions show, for two ears from different awake rabbits (A = right ear of rabbit 44 R; C = right ear of rabbit 45 R), the absolute DPOAE levels elicited by 55-dB SPL primaries for the baseline monaural (thick linewithout symbols) condition vs the delayed binaural condition (line with symbols), for f₂ frequencies tested over the selected 2-oct interval designated by the slanted-line region in each plot. (B and D) These show counterpart responses for the same rabbits illustrated in (A) and (C), respectively, while under deep anesthesia. Note only the slight variability in baseline DPOAE levels between the two states of consciousness in contrast to the decreased adaptation index, i.e., for A (8.6) vs B (1.6) for rabbit 45 R, and for C (1.5) vs D (0.8) for rabbit 44 R. Also, note that anesthesia tended to make the average DPOAE-adaptation indices more similar between different rabbit subjects (see also numeric data in Table I).