Speech teachers and singing teachers have much in common. Both attempt in their teaching to develop the most powerful and effective instrument possible while trying to avoid vocal problems. Both have studied the physiology of the vocal mechanism to assist them in their teaching. Both are concerned with the expressive qualities of the voice as well as its beauty. Both seek to develop the student's natural voice rather than an artificial imitation of some master speaker or singer. Teachers of the singing voice have developed techniques to increase resonance and power while avoiding harm to the vocal mechanism. These techniques are based on scientific principles developed from the study of vocal physiology. They allow the student to develop his or her natural voice to the highest level of technique, freeing the voice to be more expressive. These techniques have application for training of the speaking voice as well. Includes exercises for developing the voice are attached. (Contains 18 references.) (RS)