Objective: To determine the effectiveness of the self-training breathing exercise on pulmonary function in teachers.
Materials and Methods: Thirty-four teachers performed the four steps of the self-training breathing exercise program every day for 13 weeks. The pulmonary functions were measured at pre-training and the end of the study.
Results: The self-training breathing exercise program significantly improved pulmonary functions at post-training test for force vital capacity (mean difference [MD] = 0.55; 95% confidence interval [CI] = 0.34, 0.76); forced expiratory volume in one second (MD = 0.57; 95% CI = 0.36, 0.77), and peak expiratory flow rate (MD = 1.47; 95% CI = 0.54, 2.40). Vocal nodules in 4 teachers dramatically disappeared at the end point of the study.
Conclusion: The self-training breathing exercise significantly improves pulmonary functions and remedies vocal pathologies
in the teachers. This program can be applied for enhancing pulmonary function in other professional voice users, patients
with abnormal lung functions as well as people with cleft palate who need more lung volume to compensate air leakage to nasal cavity from velopharyngeal insufficiency.

Keywords: Breathing exercise, Pulmonary function, Self-training breathing, Cleft palate