8 巻 (1998) 2 号 p. 83-86
To determine the indication of cochlear implant, an electrical auditory test on the promontry isperformed to investigate sense of sound at the auditory nerve or the nerve terminal. However, theroutinely used promontry stimulation test requires penetration of the tympanic membrane. Becauseof this harmful procedure, the promontry stimulation test is not easy to apply to normal subjects.
Recently, one electroaudiometer has developed by MED-EL which has adopted a non-invasivemethod. A silver ball electrode is placed near the tympanic membrane to give electrical stimulationto the cochlea.
Using this procedure, we investigated how people with normal hearing can feel electrical stimulation.Our results showed that no one could feel the stimulation as sound at low frequency of electricpulse, but considerable number of people could feel the stimulation as real sound at high frequencyof electric pulse. This auditory sensation could possibly be caused by electrophonic effect.
This electroaudiometer with a silver ball electrode is less harmful and easily used for varioussubjects.