Tomatis’s research in the area of the singing voice quickly lead him to orient himself toward another center of interest, the speaking voice and learning foreign languages.

As it happened, Tomatis received several Venetian singers in his cabinet who all had the same phonetic problem: they couldn’t pronounce a rolled “r” and instead produced a “lll”, which is characteristic of the Venetian accent, but a real handicap for singing Opera. Instantaneously, all were capable of pronouncing a “r”. They were therefore “deaf” to the “r” , contrary to Caruso who, being Neapolitan, could reproduce this phoneme with great ease.

He therefore recorded French people, Spanish people, English people and Germans, thus obtaining for each linguistic population a large corpus of spoken words and phrases. From this data, he then established, for each language, an average response curve characteristic of the sonorities of the language, thanks to sound images accumulated with the help of panoramic analysers and sonographs. However, as these curves are very different from each other, they clearly show that each language possesses a specific position of frequential agglutination through its average response curve: the linguistic pass band. The pass band is the preferential frequency spectrum of linguistic analysis.

Different pass bands thus came to be determined over several years. For example the pass band of French is situated principally between 1000 and 2000 Hz, that of English between 2000 and 12,000, and so on.

But what determines the linguistic pass band of a given language?

It is the atmosphere. In fact, the air does not present the same vibratory characteristics in all places. The state of resistance is not always the same. This state of resistance of the air is called “impedance” and it is impedance which determines the state of adaptation of the middle ear. Indeed, according to the pass band it wishes to decode, the ear will “zoom in” on the sounds it wishes to listen to, thanks to its middle part. In the middle ear there are two small and very important muscles which will tense in a certain way in relation to the vibratory state of the air.

This particular regulation will in turn cause the inner ear to function according to a particular filtering, that is to say it will lead it to favour the reception of certain frequencies over others. These frequencies constitute the pass band. It is thanks to impedance that it is easier to speak Spanish in Spain than in France. It is what, on a micro scale, causes a person to speak with a different timbre according to whether he or she is in a room where there are vibrations or in a soundproof room.

The range of languages spoken by human beings is characterized by a great diversity in sounds, since there exist in the world approximately 600 consonant sounds and 200 vowel sounds. However, each language only uses on average around forty basic sounds, called phonemes. (Nonetheless, there is strong variability from one language to another. For example, Hawaiian only possesses 11 phonemes, against 37 for English and French, and up to 60 for certain African dialects).

The phoneme is the smallest unit of sound which creates a difference of meaning between two words (for example between “rat” and “mat”).

A given language is characterized therefore by a certain number of phonemic categories, separated on a perceptive level by well established sound frontiers, this division varying quite strongly from one language to another.

As adults, we can have a lot of difficulty discriminating certain contrasts of sounds which do not belong to our native tongue. It is precisely for this reason that it can be very hard to learn a foreign language. For example, the Japanese cannot discriminate the phonetic frontier existing in French between “r” and “l”.

The ability of phonetic discrimination in newborn babies can be attributed to general processing mechanisms of the auditory system, rather than to a perceptive mechanism developed specially for language purposes. The fact of discriminating the phonetic units of speech at birth does not imply the existence of a biologically determined and innate knowledge of these units, but simply indicates the auditory system’s ability to discriminate between them.

The child will have to both select the acoustic elements compatible with his linguistic environment, and neglect hearing those which are absent from the phonetic structures which he perceives in his habitual environment: a process of linguistic encoding will take place through adjustment to the acoustic structures of his own language.

But this encoding, because it is specific to each language, will rapidly constitute a impediment to learning a foreign language insofar as the foreign language does not conform with the sound patterns of the native language internalized from early childhood.

The linguistic sound systems are founded on the general properties of how the auditory system functions. In short, one could say that it is the ear which shaped languages.

Thus, any approach to language learning should initially aim to liberate people as much as possible from their internalized speech patterns, while helping them to appropriate to the maximum the linguistic sound patterns of the language to be learned.

In fact, it is these same principles, corresponding to phases of language development, which came to be applied to languages learning. The Tomatis® Method makes a person experience the linguistic journey of an English child, a French child, a German child, a Japanese child, and so on, which corresponds to the language to be learned. This is why we speak of “linguistic integration”, which goes further than the simple notion of learning. The person is given the possibility of appropriating and of integrating the rhythms, intonations and sonorities of the language being studied, that is to say, the music of the language.

Let us recall that the sound combinations of a language depend, in the first place, on the geographical setting itself and on its acoustic resonances because the openness of the auditory diaphragm during listening is centered on the optimal pass bands of the place in question.

These acoustic parameters (pass band and latency time) can be found in folk songs which embody modulations and cadences, that is to say the musical aspect of a language A Spanish nursery rhyme is distinct from a French nursery rhyme which itself is distinct from a German nursery rhyme. This is why folk songs are important, since they contain the phonological heritage of a language.