Spontaneous otoacoustic emissions in the bobtail lizard. III: Temperature effects.

Spontaneous otoacoustic emissions (SOAE) in the ear canal of the Australian bobtail lizard are temperature sensitive. They shift their frequency up with an increase in temperature, an effect that is fully reversible. The degree of shift is dependent not only on the center frequency of the SOAE (lower-frequency SOAE show a smaller shift) but also on the temperature range in question. Rates of change of frequency are 0.014 to 0.04 oct/degrees C at 30 degrees C, and twice that at 22 degrees C. There was no strong and consistent effect of temperature on SOAE amplitudes. The above findings are very similar to those on the effect of temperature on SOAE of frogs and mammals. Suppression tuning curves of SOAE shifted with temperature, the largest effects being near the center frequency in the tuning-curve's tip region.