EURASIP Journal on Applied Signal Processing 
Volume 2003 (2003), Issue 7, Pages 639-648
doi:10.1155/S1110865703303026

An Analogue VLSI Implementation of the Meddis Inner Hair Cell Model

Alistair McEwan and André van Schaik

 Computer Engineering Laboratory, School of Electrical and Information Engineering, University of Sydney, 2006, NSW, Australia
Received 18 June 2002; Revised 23 September 2002

Abstract

The Meddis inner hair cell model is a widely accepted, but computationally intensive computer model of mammalian inner hair cell function. We have produced an analogue VLSI implementation of this model that operates in real time in the current domain by using translinear and log-domain circuits. The circuit has been fabricated on a chip and tested against the Meddis model for (a) rate level functions for onset and steady-state response, (b) recovery after masking, (c) additivity, (d) two-component adaptation, (e) phase locking, (f) recovery of spontaneous activity, and (g) computational efficiency. The advantage of this circuit, over other electronic inner hair cell models, is its nearly exact implementation of the Meddis model which can be tuned to behave similarly to the biological inner hair cell. This has important implications on our ability to simulate the auditory system in real time. Furthermore, the technique of mapping a mathematical model of first-order differential equations to a circuit of log-domain filters allows us to implement real-time neuromorphic signal processors for a host of models using the same approach.