The nonlinearity of the basilar membrane motion observed by Rhode can be accounted for by assuming that the linear losses (proportional to the membrane velocity) are supplemented by nonlinear losses—particularly losses proportional to the velocity raised to the third power. In this paper, the consequences of such a nonlinear‐loss law for the combination tone 2f1−f2 (the lower ’’cubic difference tone,’’ DCT) are examined. In agreement with experimental data, the amplitude of the CDT is found to approach a cube‐root dependence on the primary stimulus amplitudes when the two primary amplitudes are varied proportionally. When one primary amplitude is held fixed, the calculated CDT‐amplitude goes through a maximum when the other primary amplitude is increased—again as observed experimentally. In the model, this noteworthy amplitude behavior is a direct consequence of the cube‐root dependence of the membrane velocity on pressure for large pressures which has an amplitude limiting action on the generation of the CDT. The basic properties of the CDT, as primary amplitudes and frequencies are varied, can be approximated by assuming that the 2f1−22 distortion component is generated predominantly at one place (near the characteristic place for f2).
Subject Classification: 65.26, 65.56.