Laryngeal muscle activities during phonation and swallowing in non-dysphonic and dysphonic subjects

Phonation and swallowing involve similar group of laryngeal and neck muscles. This study investigated the muscle activities of the suprahyoid (digastric, mylohyoid, geniohyoid and stylohyoid) and infrahyoid (thyrohyoid) muscles during phonation and swallowing using surface electromyography (sEMG). Fifteen non-dysphonic and six dysphonic subjects with unilateral vocal fold paralysis participated in this study. The phonatory tasks involved comfortable, low and high pitch productions while the swallowing tasks included dry swallow, and swallowing 5ml and 10ml of water. The results showed that the muscle activities during the phonatory tasks were significantly smaller than those of the swallowing tasks in both subject groups. However, no significant differences were found in the muscle activities between the non-dysphonic and dysphonic subjects in the phonatory and swallowing tasks. The findings indicate that swallowing requires higher muscle activities which is hypothesized to be attributed to the extra effort in laryngeal elevation that is required to protect the airway