Here’s a fascinating video, reportedly from a 1930 newsreel, in which Helen Keller’s teacher Anne Sullivan shows how she taught Keller to speak out loud.
In the video, Keller places her hand in such a way that she can feel Sullivan’s larynx with her thumb, lips with her first finger, and nose with her middle finger. This allows her to understand which sounds Sullivan is making and to repeat them and put them together into syllables and words.
The video is short but amazing to watch (linked from YouTube):
AB — 20 August 2009
A Thinking Person, a.k.a. Cogit8R 
Wow! Pretty amazing video you found to share!