After much self observation in front of a mirror, he noticed that when he went to speak he pulled his neck back and down, depressed his larynx, and sucked in breath with a gasp. He began to see that if he didn't pull his neck back and down when he spoke his larynx was not unduly depressed, he didn't lose his voice, he didn't gasp and the quality of his voice was much improved.
This information was the basis of his discovery of the relationship between the head, neck and torso in body movement. Further discovery revealed how the head, neck and torso relationship not only positively affected voice, but all aspects of movement.