Videoendoscopic analysis of laryngeal function during laughter.

Although commonly encountered in all human cultures, laughter remains poorly understood. In order to examine laryngeal function during laughter, telescopic and fiberscopic videolaryngoscopy was performed on five subjects, who laughed in the different vowels, at various frequencies, and in several voice qualities. During laughter, the vocal folds were found consistently to undergo rhythmic abduction and adduction. At the end of these specific phonation tasks, all subjects were able to gain voluntary control of paramedian vocal fold positioning. This study defined laryngeal function during laughter. These results have important clinical implications. Voluntary vocal fold positioning has important applications in speech therapy for dysphonias, such as vocal fold nodules, in which the primary cause is vocal fold hyperadduction. Patients suffering from these hyperadductive dysphonias may be able to utilize laughter to correct them.