A computer-based test system for implementing pure-tone audiometry, acoustic immittance and tympanic membrane displacement measurements.

Valuable information on functional features of the auditory system may be gained by measuring the fine structure and time course of the acoustic stapedial reflex. This type of measurement invariable needs a computer for averaging the reflex response and the analysis of its salient features. This paper describes a 'Computerised Audiometric System' (CAS) which allows an integrated approach to certain audiometric tests, including pure-tone audiometry and tympanometry. In particular, 'tympanic membrane displacement' and acoustic immittance measurements have been combined to allow a comprehensive study of the reflex characteristics to be made. The purpose of this paper is twofold; first to describe the CAS in respect of reflex measurements; secondly, to describe the design of a practical computerised audiometric system which may be used for a wide variety of clinical testing and research. Features of special mention are the modular design strategy used, which makes the system an extremely versatile research tool as well as a potentially valuable addition to the audiology clinic, and menu-driven software written in FORTH, which allows complex test paradigms to be learnt and reliably implemented with a minimum of training. The prototype facility has been used extensively for research over the past 18 months, and a second is now installed in the Wessex Regional Audiology Centre. Both facilities will be linked to a patient data bank now under development.