Unification and extension of monolithic state space and iterative cochlear models

Abstract

Time domain cochlear models have primarily followed a method introduced by Allen and Sondhi [J. Acoust. Soc. Am. 66, 123-132 (1979)]. Recently the "state space formalism" proposed by Elliott et al. [J. Acoust. Soc. Am. 122, 2759-2771 (2007)] has been used to simulate a wide range of nonlinear cochlear models. It used a one-dimensional approach that is extended to two dimensions in this paper, using the finite element method. The recently developed "state space formalism" in fact shares a close relationship to the earlier approach. Working from Diependaal et al. [J. Acoust. Soc. Am. 82, 1655-1666 (1987)] the two approaches are compared and the relationship formalized. Understanding this relationship allows models to be converted from one to the other in order to utilize each of their strengths. A second method to derive the state space matrices required for the "state space formalism" is also presented. This method offers improved numerical properties because it uses the information available about the model more effectively. Numerical results support the claims regarding fluid dimension and the underlying similarity of the two approaches. Finally, the recent advances in the state space formalism [Bertaccini and Sisto, J. Comp. Phys. 230, 2575-2587 (2011)] are discussed in terms of this relationship.

Transmission line cochlear models: Improved accuracy and efficiency

“…The state space model, i.e., the formulation of the cochlear dynamics through a set of coupled, first-order differential equations, can be applied to a large family of cochlear models (Elliott et al, 2007), and it has been used by Bertaccini and Sisto (2011) in conjunction with a hybrid solver for fast numerical simulations. The connection between the method proposed by Diependaal et al (1987) and the state space model has recently been discussed by Rapson et al (2012).…”

Model based prediction of the existence of the spontaneous cochlear microphonic

“…This observation is compatible with similar modelling approach such as [6,19,21]. For assessing the transient behaviours of the model including poles having positive real parts, time-domain analyses (using the approach of [2]) are performed to investigate the effect of step changes of α v .…”

“…Our model does not necessarily include the minimum frequency spaces for SOAEs that Shera [23] reports but which are challenged by Braun [4]. It was shown that small rapid perturbations in feedback gain which have been previously hypothesised to be the generation source of SOAEs [6,19,21] can also generate Spontaneous Cochlear Microphonic (SCOMIC). Currently the SOAEs and SCOMIC generated by our model are localised to particular places along the BM associated with random irregularities.…”

“…However there is not yet widespread agreement on the exact mechanisms involved in generating SOAEs. From a modelling vantage point, abrupt changes in the cochlear amplifier gain of the human cochlear model can cause oscillations in the basilar membrane that can be detected in the ear canal as SOAEs [6,19,21].…”

Development, validation and application of a generator for distortion product otoacoustic emissions

“…Within this hardware setup, various models could be implemented in signal processors for the fundamental DPOAE generation mechanisms-such as advanced models by Liu et al [9], Neely et al [10], Rapson et al [11] and How et al [12]. However, since the focus is on designing a generic tool, useful for the development and testing of OAE devices and protocols, a less complex DPOAE generator algorithm is proposed in this paper.…”