Development of a Stimulator for Elicitation of Auditory Evoked Potentials by Japanese Words.

点击翻译按钮获取中文摘要

An auditory stimulater using Japanese words for auditory evoked potentials was developed. This stimulator generates two tone bursts of different frequencies, and two different words at random. Several pairs of Japanese words whose first sound was the same and the other was different were chosen for the stimulation. Finally the following 6 pairs were selected: "A-ka, A-o"; "A-shi, A-me"; "I-nu, I-su"; "Ku-ma, Ku-tsu"; "Ha-na, Ha-to" and "Sa-ru, Sa-ra". those which had a vowel as the first sound were clearly differentiated, however, those which had a consonant, especially fricative sound as the first sound such as "Sa-ru; Sa-ra" were equivocally differentiated. It is likely due to the analog to digital conversion of the machine was less sensitive to the fricative sound.For the elicitation of P300, one tone burst was given at 20% and the other was given at 80%. The tone burst which was given at low frequency was used as the target stimulation. The sound stimulation was also given at 20 and 80% for each word. P300 was derived form the vertex referred to the linked ear lobes.The P300 could be elicited by this sound stimulation of paired Japanese words of "A-ka which means red" and "A-o which means blue" as well as by the tone burst stimulation. In a 4-year-old boy, the tone bursts could not elicit P300, but the sound stimulation could. It is proved that this equipment is useful for elicitation of P300 even in children whose P300 cannot be evoked by tone burst. The latency of P300 was longer by sound stimulation than by tone burst. This difference probably relate to time delay of discrimination of the two words by the second sound.The response time evaluated by button press task was also delayed for the word discrimination than for the tone discrimination.