The sharply tuned sense of hearing in humans is believed to be due to active mechanical amplification in the cochlea. One apparently natural consequence of this ‘cochlear amplifier’is the existence of spontaneous otoacoustic emissions (SOAEs), narrow-band tones that are detected in the ear canals of approximately half of all normal-hearing individuals. Authors have argued that SOAEs are created by multiple reflections between the middle ear boundary and a dense array of inhomogeneities scattered throughout the cochlea. This theory is contrary to previous ideas which assume independently unstable oscillators in the cochlea. This work uses a state space formulation of the cochlea to test the predictions of the multiple-reflection theory of SOAE generation in humans. In this model, the local mechanics of discretized segments of the cochlea are represented by lumped elements. Each section includes a frequency-dependent active feedback loop which enhances the motion of the basilar membrane (BM), a thin sheet that divides the cochlea into two fluid-filled chambers. The activity of adjacent segments of the model is coupled together by the cochlear fluid. The linear stability of the cochlear model is evaluated by calculating the eigenvalues of the system matrix. Instabilities arise across a wide bandwidth of frequencies when the smooth spatial variation of BM impedance is disturbed. The salient features of the multiple-reflection theory are observed in this active model given perturbations in the distribution of feedback gain along the cochlea. Spatially random gain variations are used to approximate what may exist in human cochleae. The average spacings of adjacent unstable frequencies agree with the most commonly observed value in human SOAE data. Nonlinear time domain simulations of unstable models illustrate how instabilities in the cochlea develop into limit cycles similar to SOAEs.