Study of the Acoustic Reflex Feedback Loop

The acoustic reflex is a regulator, which is thought to act as a protective mechanism in limiting the magnitude of high level sounds before they reach the cochlea. The reflex was studied via measuring the variation of the mechanical input impedance to the ears of human subjects. The auditory system was stimulated with high intensity white noise. Step responses were studied, and the system was shown to be nonlinear in that response characteristics were dependent upon the sign of the velocity. A piecewise linear model was derived from the transient response. By using external feedback, the system was rendered oscillatory. The resulting limit cycle was studied with the phase plane method.