Speech Sound Disorder: What is it?

Speech Sound Disorder (SSD) involves difficulty with and/or slowness in the development of a child’s speech. The term ‘speech sound disorder(s)’ is an umbrella heading under which there are several sub-categories that include articulation disorder, phonological disorder and childhood apraxia of speech. Speech sound disorder is sometimes called ‘speech impairment’ or ‘speech difficulties’.

It occurs when a child does not develop the ability to produce some or all sounds necessary for speech that are normally used at his or her age.

Children with phonological disorder do not use some or all of the speech sounds expected for their age group.

There are many different levels of severity of phonological disorder. These range from speech that is completely incomprehensible, even to a child’s immediate family members, to speech that can be understood by everyone but in which some sounds are slightly mispronounced. Treatment for phonological disorder is important not only for the child’s development to be able to form speech sounds, but for other reasons, as well. Children who have problems creating speech sounds may have academic problems in subject areas such as spelling or reading. Also, children who sound different than their peers may find themselves frustrated and ridiculed, and may become less willing to participate in play or classroom activities.


This disorder is more common in boys. About 3% of preschool children and 2% of children ages 6 – 7 have the disorder.

The cause of phonological disorder in children is often unknown. Close relatives may have had speech and language problems. Other risk factors may include poverty and coming from a large family.

Phonologic disorders may also be caused by:

  • Problems or changes in the structure or shape of the muscles and bones that are used to make speech sounds. These changes may include cleft palate and problems with the teeth.
  • Damage to parts of the brain or the nerves that control how the muscles and other structures work to create speech (such as from cerebral palsy).


Most children have problems pronouncing words early on while their speech is developing.

However, by age 3, at least half of what a child says should be understood (intelligible) by a stranger.

By age 5, a child’s speech should be mostly intelligible.

  • The child should make most sounds correctly by age 4 or 5, except for a few sounds such as l, s , r , v , z , ch , sh , and th .
  • Some of the more difficult sounds may not be completely correct, even by age 7 or 8.

Children with phonological disorder will substitute, leave off, or change sounds. These errors may make it hard for other people to understand the child. Only family members may be able to understand a child who has a more severe phonological speech disorder.

Commonly, children with this disorder have:

  • Problems with words that begin with two consonants. ” Friend ” becomes ” fiend ” and ” spoon ” becomes ” soon .”
  • Problems with words that have a certain sound, such as words with ” k,” ” g ,” or ” r .” The child may either leave out these sounds, not pronounce them clearly, or use a different sound in their place. (Examples include: “boo” for “book,” “wabbit” for “rabbit,” “nana” for “banana,” “wed” for “red,” and making the “s” sound with a whistle.)



The prognosis for children with phonological disorder is generally good. For many children, the problem resolves spontaneously. It is reported that in 75% of children with mild-or-moderate forms of the disorder, and whose problems do not stem from a medical condition, the symptoms resolve before age six. In many other cases, children who receive treatment eventually develop normal or close to normal speech. In some cases, there may be mild effects that last until adulthood, but speech is completely understandable. For children with phonological disorder due to a neurological or structural cause, the outcome generally rests on how well the cause of the problem is treated.
It is important to have your child’s speech assessed by a speech and language therapist to start an appropriate therapy plan.

Sharp HM, Hillenbrand K. Speech and language development and disorders in children. Pediatr Clin North Am . 2008;55:1159-1173.

Simms MD. Language disorders in children: classification and clinical syndromes. Pediatr Clin North Am . 2007;54:437-467.

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