Great singers control their voices through bone conduction. So these four factors became very important in Tomatis' theories regarding the treatment of listening disorders. By the 1950's he had identified these following principals. The voice can only produce what the ear can hear The leading ear has a role in the establishment of audio-vocal control. The body has an important role in self-listening.
Bone conduction plays an important role in self-listening.
To listen and to listen to one-self are voluntary acts, recent achievements of evolution, while to hear is purely automatic. Listening is quickly replaced by hearing if any unfortunate experience occurs to break up the marvelous but unsteady functional structure. And he felt that all of these were ultimately associated with laterality. Tomatis looked at the role of the leading ear in stuttering. This was from his finding that when he masked the leading ear some people with normal phonation they actually started to stutter.