抄録
Articulatory mechanism of bilabial and velar consonants was investigated electromyographically with seven normal adults and four cleft palate speakers. Muscles investigated were the orbicularis oris, genioglossus, mylohyoid, levator veli palatini, lateral cricoarytenoid and vocalis muscles. The results are summarized as the followings:
A. In normal speakers,
1) The orbicularis oris muscle presented marked activity for bilabial consonants as described in previous reports. 2) The mylohyoid muscle showed marked peak activity prior to velar stops. In the genioglossus muscle, no consistant participation in producing velar stops was found. 3) The levator veli palatini muscle, in general, was active for oral sounds and inactive for nasal. Its activity, however, did not remain in the same level during successive oral sounds, but showed significant variations. Especially, for plosives the levator veli palatini often went with the bilabial or the mylohyoid muscle. 4) For the voice bar of initial voiced stops, the levator veli palatini was inactive. 5) Some contextual variations were found in the activity of each muscle. 6) The lateral cricoarytenoid and vocalis muscles, though both being adductors of the vocal cords, were activated in some different ways during speech sounds utterances.
B. In cleft palate speakers,
1) The activity o f the orbicularis oris was less marked for bilabial stops than in the normal subjects. 2) The activity mode of the levator veli palatini was rather similar to that in the normal. 3) The adductor muscles of the vocal cords presented marked peak activity for stop consonants which indicated a gesture for glottal stop.
