Digital technology and clinical practice: the outlook for the future.

Digital technology has made important contributions to the field of audiology . In the past few years the computer has been incorporated into many pieces of equipment that are essential to the practice of audiology . For example, audiometers are now microprocessor-based, the computer is essential to the equipment used to measure the auditory evoked response, and the newer hearing aid measurement systems are computerized, as are probe microphone systems . In some instances, the fact that a clinical instrument is computer-based has little effect on the way clinical testing is done or on clinical management of a case . The fact that an audiometer contains a microprocessor does not necessarily cause a change in the clinical procedures to be used, or even in the manner the procedure is carried out . In other instances, availability of the computer stimulates the development of new methods and procedures that extend clinical resources and improve the ability to provide services to hearing-impaired persons. Without the capability of averaging a large number of time-locked responses to sound, measurement of the auditory evoked response would not be possible. Averaging could be done using analog equipment, but brain stem audiometry might not have become a viable clinical tool were it not for the computer, which made the procedure truly efficient . Once the technology for measuring auditory evoked potentials became available, its potential for clinical use became evident . It is presently used for identification of hearing loss in difficult-to-test patients and for neuroaudiologic testing . New techniques continue to be developed (e .g., brain electrical activity mapping). In the case of hearing aid measurement systems, digital technology has made it possible to measure the electroacoustic characteristics of a hearing aid more efficiently . New methods for measuring the output of hearing aids are also feasible because of the special properties of computer-based systems. For example, real-time spectrum analysis of the output of the hearing aid enables the use of a complex stimulus rather than a pure tone stimulus as the test signal . This type of analysis is particularly useful for the measurement of nonlinear hearing aids (e .g., compression aids and "automatic signal-processing" aids) . The use of a complex stimulus allows for more accurate measurement of the performance of nonlinear hearing aids in the low frequency region than does the use of a pure tone stimulus . It is expected that new measuring techniques will be developed to further realize the potential of the computer. Although probe microphones have been used by researchers for many years, clinical use of these microphones is very recent . Computerization makes the calibration of the probe microphone systems simple and efficient . Probe microphone systems enable the clinician to make real ear measurements of the electroacoustic characteristics of the hearing