Quantitative Evaluation of Limit-Cycle Oscillator Models of Spontaneous Otoacoustic Emissions

Abstract

Single limit-cycle-oscillator models of spontaneous otoacoustic emissions (SOAE’s) are based on the assumption that the pattern of interactions between spontaneous emissions and external tones in the ear canal may be partially described by the gross compaction of a full cochlear model to a single nonlinear differential equation such as that of a free (or driven) Van der Pol oscillator. Such an equation incorporates, in a highly idealized way, the type of nonlinear-active damping which, if assumed to be present over certain portions of the cochlear partition, would produce stabilized cochlear self-oscillations and lead to measurable spontaneous emissions in the ear-canal. These models have been used successfully by our group and by Wit and collaborators to account for a number of features of the emission data including: a) statistical properties of emissions (e.g. Bialek and Wit, 1984; Wit, 1986; van Dijk, 1990); b) suppression of emissions (Long and Tubis, 1990) and synchronization (phase locking) of emissions by external tones (e.g., van Dijk, 1990; Long, et al., 1990); and c) reduction of the level of emissions by aspirin consumption (e.g., Long and Tubis, 1988a,b).