Ipsilateral Acoustic Reflex Artefacts Measured in Cadavers

Abstract

Ipsilateral acoustic reflex eliciting stimuli were presented via the probes of six impedance meters to cadaver ears to determine the minimum stimulus levels at which apparent impedance changes occurred. These artefactual indications of impedance change were detected in all but one instrument within the range of intensities available for all frequencies tested. The remaining instrument employs a pulsed stimulus technique which attempts to avoid the artefact problem, and this device only produced artefacts at one frequency and at relatively higher levels than the other instruments. Attempts were made to increase the minimum intensities at which artefacts occurred by introducing various pressure differentials across the tympanic membrane. Generally only small (<10 dB) increases in the artefact threshold were obtained in this way, although with one instrument there were somewhat larger increases.