A linear electric circuit model for motions of the basilar membrane was modified by introducing nonlinear diode elements so as to represent mechanical displacements that occur more readily in one direction than in the other. The specific nonlinear site or structure in the cochlea is not necessarily represented by the model; it may be some part of the organ of Corti, it may result from rigidity of scalae walls, and/or it may arise from fluid streaming near the oval window. Patterns on linear and nonlinear ears are compared for two specific tone combinations, the simple difference tone f1 − f2, and the more complex 2f1 − f2 case. At least three explanations for perception of these difference tones, with and without presence of a third exploring tone, can be offered. Waveforms for clicks and voiced and unvoiced speech sounds are also presented, and similar phenomena are observed. In general, strongly augmented activity occurs in the apical part of the cochlea when nonlinearities exist, and for the 2f1 − f2 component, an unusual pattern also occurs in the region most responsive to f2.