ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4aPP1. Relaxation dynamics of spontaneous otoacoustic emissions perturbed by external tones: Response to a single tone at multiple suppression levels.

William J. Murphy

Bioacoust. and Occup. Vib. Sect., Natl. Inst. for Occup. Safety and Health, MS C-27, 4676 Columbia Pkwy., Cincinnati, OH 45226-1998

Arnold Tubis

Carrick L. Talmadge

Purdue Univ., West Lafayette, IN 47907-1396

The relaxation dynamics of spontaneous otoacoustic emissions (SOAEs) interacting with an external tone have been successfully described using a Van der Pol limit-cycle oscillator model [Murphy et al., J. Acoust. Soc. Am. 97, 3702--3711 (1995a) and Murphy et al., J. Acoust. Soc. Am. 97, 3712--3720 (1995b)]. The theory developed in Murphy et al. (1995a) includes the possibility for multiple external tones to produce suppression of the oscillator amplitude. The relaxation dynamics are dependent upon the final state of the oscillator. The oscillator's rate of transition between two suppressed states is a function of (kappa)[inf 2][sup 2]r[inf 1], the final amount of suppression and the negative damping parameter r[inf 1]. Data were collected from an SOAE interacting with a single frequency ipsilateral suppressor. Transitions between different suppressed states were achieved by adding or removing signal at the same frequency. The ability of the relaxation dynamics theory to describe this special case will be examined.