Figure 3.

The group delay (ms) of the distortion product as a function of frequency (kHz) of the tenrec (solid line). For comparison, data from the gerbil (dashed line) and the opossum (dotted line) are shown. To determine the group delay, f₂ was held constant while f₁ was decreased in small steps. For each f₁ step, the 2f₁ − f₂ DPOAE level and its phase was determined as a function of the 2f₁ − f₂ frequency. Fromthe change in DPOAE phase relative to the change in frequency, the mean group delay values were calculated over all values for which the ratio curve was at least 6 dB above noise floor.