Efficacy of Seo Dong-Il's Technique as a Method of Improving Voice Quality in Patients with Phonasthenia and Vocal Nodules

The purpose of this study was to investigate the effects of Sea Dong-Il's technique on voice quality in patients with vocal nodules and phonasthenia (vocal fatigue). Ten patients (4 nodules and 6 vocal fatigue) participated in the study. Each subject was assessed acoustically (Fo, Jitter, Shimmer, NNE) in the first and last session. Dr. Speech (version 3.4, Tiger-DRS) was used to compare acoustic parameters of pre-and post-treatment. Sea Dong-Il's technique consisted of breathing exercise, relaxation exercise, and phonation exercise. The results were as follows: First, Sea Dong- Il's technique tended to be effective on improving voice quality in patients with phonasthenia and vocal nodules. Second, the nature of improvements were as follows: there was a significant difference between pre-and post-treatment in shimmer (p < .01) and NNE (p < .001), while there was no significant difference between pre-and post-treatment in Fo and Jitter. Finally, given the fact that the number of subjects was only 10, the jitter might have shown a significant difference if more subjects participated in the experiment.