Background: Teachers are professional voice users that routinely need voice for daily professional activities. The volume of air in the lung is the main factor that supports speech production. Maximum phonation time (MPT) is an indicator of this factor. Breathing exercises are used to augment diaphragmatic descent while inhalation and ascent during expiration to improve the MPT.
Objective: To examine the effects of self-training breathing exercise on increasing MPT in teachers.
Material and Method: Thirty-four teachers enrolled in the self-training breathing exercise program, comprising 4 steps, 20
sessions (2 sessions per day), and every day practice for 13 weeks. The MPT and maximum counting duration (MCD) were
measured at 1st (pre-test), 4th, 7th, 10th, and 13th week.
Results: The self-training breathing exercise program significantly improved MPT at the end of the 4thweek for /i/ and all vowel prolongation and MCD at 7th week. There were significantly increased of MPT and MCD in all vowels at the end of the study: /a/ {mean difference (MD) 2.89; 95% confidence interval (CI) = 1.44-4.34}, /u/(MD 4.22; 95% CI =2.8-5.60), /i/ (MD 5.86; 95% CI = 3.90-7.81), and MCD (MD 5.82; 95 % CI = 4.44-7.19).
Conclusion: The self-training breathing exercise significantly improved MPT and MCD in teachers. This program can be
implemented to enhance MPT and MCD in other professional voice users, as well as children or people with cleft palate who
are at risk for voice disorders.

Keywords: Breathing exercise, Maximum phonation time, Voice professional users, Cleft palate