Autism is a pervasive development disorder (PDD). PDDs are severe and early developing disorders, characterised by retardations and alterations in the development of social interaction, cognitive and communication abilities.

According to the international classification of illnesses and the DSM-IV (Diagnostic and Statistical Manual - Revision 4), the symptoms which define autism are as follows:
- Early development of disorders, before the age of 3
- Serious difficulties with social interaction
- Severe anomalies in language development
- Restricted, repetitive and stereotyped behaviour, interests and activities
- Abnormal sensorial responses, reflecting hypersensitivity or hyposensitivity

It is of course obvious that the Tomatis method only represents one of the many possible approaches to help the autistic child, and in no case can it be considered to be sufficient in itself.
However, it can be a very useful ally when working to improve this disorder, because it can very efficiently help the autistic child on several levels.

First of all, considerable work is undertaken with the mother's voice: the child will be re-immersed in the sonic environment of the womb to try to induce in him or her a desire to communicate.
By transmitting the mother's voice with strong participation of bone conduction, the idea is to awaken in the child the awareness of a primordial and indissoluble bond rooted within him.
It is interesting to observe the strong power of regulation in the maternal voice: very often, the child becomes instantaneously calm when listening to it and gives us the impression that he or she is remembering this voice and recognising it.
In concrete terms, the aim is to establish contact with the child, by stimulating him or her through very specific work in bone conduction. This work will help to provide a clearer definition of body schema, because the perception of the bone structure generates awareness of the unity of the overall body structure.
Furthermore, working on bone conduction will increase the sensitivity of cutaneous responses and therefore awareness of the body. This reinforcement of the responses of the skin will in turn entail greater receptivity to all vibratory phenomena, and in particular to the sounds involved in speech.
Moreover, by awakening cutaneous and therefore tactile sensitivity, we will also stimulate visual contact, because there is a functional analogy between these two senses. The gaze will then become more exploratory, and the child will start to 'feel out' his visual environment through his gaze.
Finally, it is the entire face which becomes more expressive and the child will start to use and master non verbal aspects of communication, in the way of certain mimes.
Once the ear is correctly regulated by bone conduction, there will in addition be a disappearance or reduction of fits of anger, often observed in auditory hypersensitivity hyposensitivity.
On a verbal level, when the child is already speaking, an increase in talkativeness will occur as well as an improvement in the expressive characteristics of language, through a more appropriate use of intonation contours.
Finally, this multi-sensorial approach will be all the more efficient because the auditory stimulation generates a strong increase of energy resources and thus soothe the heightened anxiety which the autistic child suffers from.
This multi-sensorial action is very important, because it helps the child to construct a coherent representation of his or her own body, and to construct relations between the body and the environment