presentations has been the most commonly used strategy in classrooms 1 , elevating vocal demand 2,3 , the voice must be intelligible, accessible, motivational as well as assertive and effective, since the ability to keep student's attention may be harmed if the voice is monotonous, weak or systematically tense and also if the teacher's speech has a deviation in speed or fluency. Thus, the voice in its professional use is highly demanding regarding communication and its good functioning is a basic requirement for the profession 4 .Teaching requires a high vocal demand that aims to socialize and build knowledge with the students who are many times noisy 5 and in not always healthy work conditions 6-8 that favor concentration 9,10 , in Appropriate vocal functioning favors the effectiveness of communication in the classroom, aids in building teachers' self-esteem and contributes with students' learning skills. Considering that oral