ASA 124th Meeting New Orleans 1992 October

4aPP14. Dynamics of self-interaction of two spontaneous otoacoustic emissions suppressed by a pulsed external tone.

W. J. Murphy

A. Tubis

C. L. Talmadge

Dept. of Phys., Purdue Univ., West Lafayette, IN 47907

The level of a spontaneous otoacoustic emission (SOAE) during recovery from suppression by an external tone sometimes exhibits a prominent overshoot before settling down to its natural value. This overshoot may be explained in terms of the suppression of the SOAE by a neighboring higher frequency emission which is slowly recovering from suppression by the external tone. This phenomena has been investigated using a pulsed suppressor tone (Talmadge et al., 1990) and averaging the amplitude envelopes of the emission for successive presentations of the suppressor. One simple version of the dynamics involves a Van der Pol oscillator with an effective external tone of the form, (Lambda)(1-e[sup -(Gamma)t])cos((omega)t). This form simulates the recovery from suppression of the higher frequency SOAE. This model has been used to extract from the data estimates of the time constants for the recovery from suppression of an emission that exhibits the overshoot phenomena. More elaborate models involving the coupling of two Van der Pol oscillators (e.g., Wit, 1990) are also considered.