An Evaluation of Electrodiagnostic Measures of Hearing

Abstract

The effectiveness of three non-invasive electrophysiological
techniques in the assessment of the subjective hearing thresholds
was evaluated in normal and hearing impaired populations.

1. The Vertex Potential was used to establish objective
auditory thresholds in normal adults and in adults and
children with known hearing defects. Comparison of subjective
and objective hearing thresholds revealed the vertex
potential to be most reliable as a measure of auditory acuity
in the group of normal adults; the groups of adult and child
hearing defects showed both greater discrepancies and variability
between subjective and objective assessment.

2. The Post-Auricular Myogenic Potential was investigated
in two groups of normal adults. It was found to provide a
less reliable assessment of auditory acuity than either the
vertex potential or the brainstem potentials mainly on account
of its variability and dependancy on resting muscle tone.

3. Brainstem Evoked Potentials were recorded in a large group
of normal adults. The N4 component (Jewett's V wave)
was found to provide a close and reliable estimation On
subjective hearing level. The observed Stability in the
characteristics of the brainstem potentials would support
their use in neurological assessment, but initial findings
indicate a need for the development of more comprehensive
age and sex related normal data.

Further investigations of the vertex potential using linguistic
and non-linguistic stimuli failed to produce any
clear evidence of the reflection of stimulus meaning in the
characteristics of the vertex potential. The results,
instead, would support the on-response nature of the vertex
potential whose characteristics are primarily determined by
the physical properties of the stimulus.

Date of Award	1979
Original language	English