The term intelligibility refers to how much a listener can understand the speaker. In typical development, as children learn to talk, their comprehensibility to those around them steadily increases. This chart gives percentage of speech that should be understandable for their age.
All children make predictable pronunciation errors (not really 'errors' at all, when you stop to think about it) when they are learning to talk like adults. These 'errors' are called phonological processes, or phonological deviations. Here are the common phonological processes found in children's speech while they are learning the adult sound-system of English.
This program serves preschool children, ages three to five who are experiencing mild delays in Head Start-State Preschool, private preschool or home settings.
More than 75% of the preschoolers exiting the program will enter regular kindergarten without the need for further special education services.