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Prolongation of the cochlear microphonic in man. Cochlear microphonic ringing.
Acta Oto-Laryngologica
|January 1, 1983
Summary
Cochlear microphonic (CM) ringing, an artifact in electrocochleography, appears in most normal subjects and many with hearing loss. This CM ringing phenomenon is linked to larger CM amplitudes in specific patient groups.
Area of Science:
- Audiology
- Neuroscience
- Otoacoustic Emissions
Background:
- Extra-tympanic electrocochleography (ECochG) is a standard audiological test.
- Cochlear microphonics (CM) reflect outer hair cell function.
- An observed artifact in ECochG recordings has been termed CM 'ringing'.
Purpose of the Study:
- To investigate the phenomenon of CM 'ringing' during ECochG recordings.
- To determine the prevalence of CM ringing in normal and hearing-impaired subjects.
- To explore the relationship between CM ringing and CM amplitude.
Main Methods:
- Routine extra-tympanic electrocochleography (ECochG) was performed.
- Acoustic stimuli were presented.
- CM recordings were analyzed for the presence of 'ringing' (more cycles than stimulus).
- CM amplitude was measured in subjects with and without ringing.
Main Results:
- CM ringing was observed in 69% of normal subjects.
- CM ringing was present in 43% of patients with various forms of deafness.
- Significantly larger CM amplitudes were found in subjects exhibiting ringing, particularly in cochlear and Ménière's disease subgroups (p<0.001 and p<0.01, respectively).
Conclusions:
- CM ringing is a common finding in ECochG, occurring in both normal and hearing-impaired populations.
- The presence of CM ringing may indicate enhanced cochlear activity or specific pathological conditions.
- Further research is needed to elucidate the precise origin and clinical significance of CM ringing.