Alfred Tomatis received his medical otorhinolaryngology diploma in Paris, 1949, and started receiving his patients, many of whom were opera singers, friends of his father – a famous French baritone. They came to show the young physician their vocal cords and ask for advice regarding tuning problems, loss or lack of voice color and timbre quality, loss of control on the vibrato, problems related to volume or vocal placement, and many other issues regarding voice, singing and speaking.

Tomatis helped them using the techniques and medicines of that time. He said that once, while trying to tighten the vocal chords of a singer, he increased the dose of strychnine to such extent, that the man was on the point of choking on scene, and still continued to sing flat.

One day, while looking at his patients’ audiograms, he found a resemblance between those of factory workers who had suffered acoustic trauma and those of the singers. He realized that in spite of their different professions, they presented a similar graphic in regard to their acoustic responses. Both had a drop in acoustic sensitivity at 4000 Hz. He examined a great number of audiograms, and after analyzing them and finding the same characteristics, he concluded that voice depends on the ability to hear, and if hearing is damaged, voice is automatically affected, too.

He performed experiments on singers, using audio filters. He had them sing in front of a microphone and he directed the sound towards an electronic machine which allowed him to reduce or amplify frequency as he liked. Then he transmitted the modified voice to the singers through headphones, thus controlling the voice emission. The results were surprising. Tomatis modified the voice of the singer the way he wanted. If he prevented the singer from hearing frequencies superior to 4000 Hz, for example, the voice immediately stopped producing those frequencies which affected the quality of the voice and the music. Likewise, when he resumed transmitting those frequencies clearly to the ear, the voice recovered all its qualities, its musicality, timbre and color.