Introduction

Audiological test methods, like various other clinical investigations, can be categorised into behavioural, subjective and objective techniques. The behavioural and subjective classes are often grouped as one.

Behavioural

These methods involve monitoring the patients' reactions to auditory stimuli. The response may be involuntary, e.g. when using the distraction technique an infant will instinctively turn to locate a sound of interest. It may also be voluntary; the more mature child undergoing distraction testing may elect to inhibit his or her response.

Subjective

These methods require the patient to volunteer a response, such as in pure tone or speech audiometry.

Objective

These methods require no voluntary indication from the patient that an auditory stimulus has been perceived. It is possible, however, for the patient to influence the results by interfering with the procedure. In a sense, the subjectivity is transferred to the clinician, who in many cases interprets the results, although machine scoring methods are being used increasingly. Objective tests are not a measure of hearing as such; they assess the integrity at various levels of the auditory pathway but not its entirety.

This chapter is devoted to a description of two objective measurements widely used in paediatric audiology, the auditory brainstem response (ABR) and the delayed evoked otoacoustic emission. The basic principles, measurement techniques, result interpretation and applications will be discussed.