  Biologically inspired auditory models play an important role in developing
effective audio representations that can be tightly integrated into speech and
audio processing systems. Current computational models of the cochlea are
typically expressed in terms of systems of differential equations and do not
directly lend themselves for use in computational speech processing systems.
Specifically, these models are spatially discrete and temporally continuous.
This paper presents a jointly discretised (spatially and temporally discrete)
model of the cochlea which allows for processing at fixed time intervals suited
to discrete time speech and audio processing systems. The proposed model takes
into account the active feedback mechanism in the cochlea, a core
characteristic lacking in traditional speech processing front-ends, which
endows it with significant dynamic range compression capability. This model is
derived by jointly discretising an established semi-discretised (spatially
discrete and temporally continuous) cochlear model in a state space form. We
then demonstrate that the proposed jointly discretised implementation matches
the semi-discrete model in terms of its characteristics and finally present
stability analyses of the proposed model.
