ABSTRACT
Pure-tone audiograms, speech audiograms and other tests using audiometers all rely on the signal of the patient; they are subjective, behavioural tests. Impedance audiometry is an objective test but gives no detailed information about the hearing thresholds, although it can be used to draw inferences about the likelihood of a hearing loss or its probable type. It was not until the development of electric response audiometry, also termed evoked response audiometry (ERA), in the 1970s that tests became available which could allow the determination of the hearing thresholds of a subject without any voluntary responses being required.
