Most children make some mistakes as they learn to say new words. A speech sound disorder occurs when mistakes continue past a certain age. Every sound has a different range of ages when the child should make the sound correctly. Speech sound disorders include problems with articulation (making sounds) and phonological processes (sound patterns).
To learn more about typical speech sound development, see How Does Your Child Hear and Talk? and Literacy and Communication: Expectations From Kindergarten Through Fifth Grade.
What are some signs of an articulation disorder?
An articulation disorder involves problems making sounds. Sounds can be substituted, left off, added or changed. These errors may make it hard for people to understand you.
Young children often make speech errors. For instance, many young children sound like they are making a "w" sound for an "r" sound (e.g., "wabbit" for "rabbit") or may leave sounds out of words, such as "nana" for "banana." The child may have an articulation disorder if these errors continue past the expected age.
Not all sound substitutions and omissions are speech errors. Instead, they may be related to a feature of a dialect or accent. For example, speakers of African American Vernacular English (AAVE) may use a "d" sound for a "th" sound (e.g., "dis" for "this"). This is not a speech sound disorder, but rather one of the phonological features of AAVE.
To see the age range during which most children develop each sound, visit Talking Child's speech chart.
What are some signs of a phonological disorder?
A phonological process disorder involves patterns of sound errors. For example, substituting all sounds made in the back of the mouth like "k" and "g" for those in the front of the mouth like "t" and "d" (e.g., saying "tup" for "cup" or "das" for "gas").
Another rule of speech is that some words start with two consonants, such as broken or spoon. When children don't follow this rule and say only one of the sounds ("boken" for broken or "poon" for spoon), it is more difficult for the listener to understand the child. While it is common for young children learning speech to leave one of the sounds out of the word, it is not expected as a child gets older. If a child continues to demonstrate such cluster reduction, he or she may have a phonological process disorder.
To see the ages at which phonological processes should disappear, go to Elimination of Phonological Processes, and for descriptions of the common processes see Phonological Processes.
How are speech sound disorders diagnosed?
A Speech-Language Pathologist (SLP) is the professional who evaluates children or adults with speech and language difficulties. The SLP listens to the person and may use a formal articulation test to record sound errors. An oral mechanism examination is also done to determine whether the muscles of the mouth are working correctly. The SLP may recommend speech treatment if the sound is not appropriate for the child's age or if it is not a feature of a dialect or accent. For children, the SLP often also evaluates their language development to determine overall communication functioning.