After determining the resonance of the vowel sounds, Helmholtz set about reproducing them. He was no less clever here than he was in figuring out how to analyze the pitches of human speech. After completing this analysis, he combined the sounds of various combinations of pitchforks until he achieved the same resonance as the human vowel. No one before had ever mechanically reproduced human speech sounds in such a conscious and accurate manner before, nor thought of vowels as purely interactions of different pitches. Helmholtz combined a very objective mind and ear to a fantastic and precise knowledge of the physics of sound in order to develop these reproductions. His knowledge and research into physics was essential to his study, as sound is ultimately a physical phenomenon. But his research into the human biological ability to produce sound was also groundbreaking, proving the breadth of his knowledge and worth as a scientist.

Part of his analysis of the sound of human...

He didn't limit himself to the sounds that came out of the speaker's mouth, but also studied the human physiology employed in forming the resonances that made up the vowels, and determined that some vowels were created using only one resonator, while other required two. The resonators Helmohltz identifies were the pharynx and the mouth cavity. These are indeed still known to be two of the resonators used to produce vowels. Later research has found that some vowels require even more resonances, but many of Helmholtz's conclusion remain valid today, and his work in this area laid the foundation for future endeavors. He never fully gave up his early observations with bottles, either and studied the way the different shapes people made with their mouths affected the sound of the vowel coming out. Modern applications such as speech therapy still rely heavily on the body of knowledge that Helmholtz basically founded and contributed much to.