Definition of Phonological disorder:

Phonological disorder is a failure to use speech sounds appropriate for the individual's age and dialect.

Causes, incidence, and risk factors:

This disorder is more common in boys. Approximately 3% of preschool children and 2% of children aged 6 - 7 have the disorder. By age 17, only 0.5% are affected.

The cause of phonological disorder in children is unknown. There may be a genetic component, since a large proportion of children with this problem have relatives with a similar disorder. Other risk factors seem to be low socioeconomic status and coming from a large family.