Effect of Speech Appliance to Prevent Levator Muscle Fatigule during Continuous Speech

• Published in: Journal of Japanese Cleft Palate Association Vol. 23; no. 4; pp. 273 - 281
• Main Authors: TACHIMURA, Takashi, FUJITA, Yoshinori, NOHARA, Kanji, WADA, Takeshi
• Format: Journal Article
• Language: Japanese
• Published: Japanese Cleft Palate Association 30.10.1998
• Subjects: cleft palate; fatigue; levator veli palatini; speech appliance; velopharyngeal incompetence; スピーチエイド; 口蓋帆挙筋; 口蓋裂; 筋疲労; 鼻咽腔閉鎖不全症
• ISSN: 0386-5185; 2186-5701
• DOI: 10.11224/cleftpalate1976.23.4_273

he purposes of this study were to clarify' whether continuous speech may induce levator veli palatini muscle fatigue for speakers with velopharyngeal incompetence, and whether a speech appliance (Bulb-PLP) in place can decrease the muscle fatigue during speech. Four patients who underwent surgery for cleft palate and required a speech appliance for improvement of their velopharyngeal incompetence, were selected as the subjects. Each subject was asked to pronounce more than 200 times /pu/ under both conditions of placement and removal of the speech appliance. A correlation coefficient between the number of pronunciations and values of smooth EMG activity of the levator muscle was calculated under each experimental condition. Absolute value of the correlation coefficient was significantly smaller under the placement condition than that under the removal condition for all subjects. Differential correlation coefficients between the two conditions were found to be statistically significant for three subjects out of four subjects. This result suggested that the levator muscle was likely to suffer from muscle fatigue with velopharyngeal incompetence left untreated and that a speech appliance in place can prevent muscle fatigue during speech. It is possible that the clinical effect of a speech appliance to improve velopharyngeal function is partly caused by its efficacy to decrease muscle fatigue.