Fig. 1.

Several input/output plots for DPOAE at 2f₁ − f₂ and 2f₂ − f₁ obtained in one frog. The different panels represent different stimulus frequencies and/or body temperatures (see labeling in the figure). L₁, L₂ maps show isoamplitude contour lines as function of the two stimulus levels. Contour lines are drawn at 5-dB intervals, with the appropriate levels given in the key. The arrows overlying the contour lines represent the phase of the DPOAEs, with one full counterclockwise rotation indicating a 2π lag. In each L₁, L₂ map, phase is relative to the phase at the highest L₁, L₂ combination, which was arbitrarily set to zero. The left column shows data obtained with body temperature at T = 22°C, whereas the center column shows results obtained when the recordings from the left column were repeated at a lower body temperature (T = 12°C). In the right column, data from the other two columns are redrawn (but with contour lines at 10-dB intervals) to facilitate graphical comparison between the DPOAE amplitudes recorded at the two body temperatures.