At the end of the 1940s, during his first experiments on audio-vocal counter-reactions, Tomatis had observed unusual changes in the behavioural dynamic of singers and actors.
According to the sound frequency zone which was imposed on them auditorily, the latter became more dynamic, adopted a more upright posture, began to breathe deeply and to speak or sing with a lot more ease; or on the contrary, slouched and quickly entered into a kind of torpor which they had difficulty pulling out of.

The latter state, characterised by an obvious loss of energy, deprived them of any possibility of producing a quality vocal emission, whether for singing or speaking, or even the desire to do so.
Only the frequencies corresponding to the zone of high-pitched sounds established the first category of reaction, of the dynamic type.

On the contrary, the low-pitched sounds, deprived as they were of high-pitched frequential components, systematically entailed the opposite reactions characterised by an increase in fatigue.

These results were subsequently repeated thousands of times, not only on singers and actors, but more generally on anyone undertaking a course of therapy under the electronic ear.

Moreover, due to the fact well established by Tomatis that the voice can only reproduce what the ear can hear and more particularly what it accepts to hear (first Tomatis law), by inducing people to favour the perception of high-pitched sounds they are consequently capable of permanently re-energizing themselves through their own voices. The voice can thus become the medium for the permanent regeneration of its own dynamic.

Indeed, sounds which are rich in high-pitched harmonics have the effect of stimulating a vast nervous network called the ‘reticular formation’, which controls the overall level of cerebral activity. This part of the brain is strongly involved in the mechanisms of alertness, vigilance and sustained attention. This is why these sounds will exert a dynamogenic action, while favouring the triggering of these mechanisms. They play a considerable role in the increase of activity in our cerebral cortex, participating in the efficiency of a high number important of processes involved in memory, concentration and learning.

One can then understand the benefit of a procedure aimed at educating or re-educating the ear to sufficiently perceive the high harmonic components of the sound messages which reach it. Consequently, any given sound can become an endless source of energization, provided it undergoes a phenomenon of appropriate filtering by the ear which consists in minimising the impact of its low-pitched components which offer little regeneration and even tire, while emphasising the high-pitched parts, which are sources of invigorating stimulation.

While improving the general state of the cerebral dynamic, a procedure of this kind thus enables any person prone to fatigue or depression to durably regain his or her full functional potential.