The speech therapy is a discipline that includes the study, prevention, evaluation, diagnosis and treatment of the pathologies of the language (oral, written and gestual) shown across disorders in the voice, the speech, the communication and the functions orofaciales.

Although the term most used in Spain and Latin America when we speak about the professional who exercises the speech therapy is of logopeda, also we can meet the terms: fonoaudiólogo, therapist of the language, logofoniatra, etc.

The pathologies on which it takes control of the logopeda are related to patients to problems:

- of voice (disfonía, aphonia)
- in the acquisition of the language (I am late, disfasia)
- in the verbal expression, the pronunciation (disartria, dislalia, disglosia)
- of reading and/or writing (dyslexia, disgrafia)
- in the expressive and/or comprehensive language (aphasias)
- of fluency of the speech (stuttering)
- of respiration, sucking, masticating and swallowing. One usually names the treatment of these problems specifically a Therapy Miofuncional and he is carried out both in babies, and in children and adults.

The figure of the logopeda is the same form fundamental, although the not only, in the treatment of such pathologies like:

- the deafness and the auditory shortcomings in general
- the mental deficiency
- the cerebral palsy
- the autism
- the patients with problems of communication for syndromes, illnesses, etc., like the Parkinson, Alzheimer's disease...

To conclude to clarify that the function of the logopeda is not to teach to speak well but in providing the persons who it need a system of communication that allows them to express itself already be by means of the oral, written language, gestual and/or pictográfico (drawings).

Aphonia: pathology in which there takes place an entire loss of the voice provoked by different factors.

Disfonía: alteration of the voice caused by different factors. It is much more frequent than the aphonia.