The mammalian cochlear consists of highly nonlinear components: lymph (viscous fluid), a basilar membrane (vibrating membrane in the viscous fluid), outer hair cells (active dumpers for the basilar membrane), inner hair cells (neural transducers), and spiral ganglion cells (parallel spikes density modulators). In this paper, a novel spiral ganglion cell model, the dynamics of which is described by an asynchronous cellular automaton, is presented. It is shown that the model can reproduce typical nonlinear responses of the spiral ganglion cell in the mammalian cochlea, e.g., spontaneous spiking, parallel spike density modulation, and adaptation. Also, FPGA experiments validate reproductions of these nonlinear responses.