  A two space dimensional active nonlinear nonlocal cochlear model is
formulated in the time domain to capture nonlinear hearing effects such as
compression, multi-tone suppression and difference tones. The micromechanics of
the basilar membrane (BM) are incorporated to model active cochlear properties.
An active gain parameter is constructed in the form of a nonlinear nonlocal
functional of BM displacement. The model is discretized with a boundary
integral method and numerically solved using an iterative second order accurate
finite difference scheme. A block matrix structure of the discrete system is
exploited to simplify the numerics with no loss of accuracy. Model responses to
multiple frequency stimuli are shown in agreement with hearing experiments. A
nonlinear spectrum is computed from the model, and compared with FFT spectrum
for noisy tonal inputs. The discretized model is efficient and accurate, and
can serve as a useful auditory signal processing tool.
