Speech Sound Disorder
Speech sound disorder (SSD) encompasses a group of communication disorders in which children have persistent difficulty articulating words or sounds correctly. Speech sound production requires both the phonological knowledge of speech sounds and the ability to coordinate the jaw, tongue, and lips with breathing and vocalizing to produce meaningful sounds. Children with speech sound disorder may have difficulty with the phonological knowledge of speech sounds or the ability to coordinate the movements necessary for speech. The communication difficulties can impede the development of children by limiting their ability to effectively participate in social, academic, or occupational activities.
While some speech sound disorders stem from physical structural anomalies, such as cleft palate, others have their origin in perceptual problems such as hearing impairment. Still others, like apraxia, in which the brain does not deliver the correct movement instructions to the target muscles, arise from neurodevelopmental problems.
Most children shorten words and syllables as they’re learning to talk, but children with speech sound disorder continue this simplification process past the age when most children can produce words clearly, generally agreed to be age 7.
The DSM-5 includes the following diagnostic criteria for speech sound disorder:
- Persistent difficulty with the production of speech sounds that interferes with the intelligibility of one's speech or prevents verbal communication
- Limitations on communication interfere with social participation or performance at school or work
- The symptoms begin early in life and are not attributable to other medical or neurological conditions
Developmental experts believe that approximately half of a child’s speech is intelligible by age 2 and most speech intelligible by age 4.
According to the Child Mind Institute, other potential signs of a speech sound disorder include:
- Leaving out sounds or substituting an incorrect sound for a correct one
- An unusually hoarse or nasal voice or sudden changes in pitch or loudness that make understanding speech more difficult
- Running out of air while talking
A speech-language pathologist tests a child's speech for how well he or she creates sounds and inspects how the child moves his or her lips, jaw, and tongue. The pathologist may also test the child’s hearing.
Speech sound disorder is not the same as a specific language impairment. Speech sound disorder expresses itself with a delayed ability to produce speech sounds, while specific language impairment expresses itself with an inability to incorporate the structures of grammar into speech. Only about 2 percent of children with speech sound disorder also have specific language impairment.
According to the National Institute on Deafness and Other Communication Disorders, the prevalence of speech sound disorder in young children is 8 to 9 percent of the population. By first grade, roughly 5 percent of children exhibit speech sound disorder.
The cause of speech sound disorder is not well understood in many cases. Children who develop speech sound disorder often have family members with a history of speech or language disorder, suggesting a genetic component of this condition. Speech sound disorder may occur along with other delays in the use of facial musculature, such as difficulties in chewing, maintaining a closed mouth, and blowing one’s nose
Hearing impairment or deafness do often result in abnormalities of speech sounds. This does not mean someone with a hearing impairment has a neurodevelopmental speech sound disorder. For instance, a child who receives cochlear implants may be able to catch up to peers in speech sound production due to their new ability to hear others better.
Speech sound disorder is a neurodevelopmental disorder unrelated to anxiety. The disorder could, however, lead to anxiety in children who are unable to fully express themselves. Such anxiety could be expressed as selective mutism, where children do not speak in certain circumstances due to embarrassment.
There is substantial research suggesting the heritability of speech sound disorder. Studies have demonstrated familial aggregation for SSD, where approximately 26 percent of nuclear family members and 13.6 percent of extended family members were affected in a cohort of children with SSD.
Treatment for speech sound disorder primarily consists of speech and language therapy. A speech-language pathologist typically develops a treatment plan that helps a child identify and correct the specific sounds or words they have difficulty articulating. The speech-language pathologist may show the child how to move their tongue and lips to produce sounds correctly and provide opportunities to practice these skills.
In most cases, children with speech sound disorder respond well to speech therapy; speech difficulties improve over time. The condition appears to resolve in 75 percent of children by age 6. When a language disorder is also present, however, speech sound disorder has a poorer prognosis and may be associated with learning disorders.
According to the American Speech-Language-Hearing Association, treatment is generally done with the help of a speech pathologist and focusing on: establishing a target sounds to work on producing reliably, working up from syllables to words to sentences, and, finally, stabilizing this sound production to the point where the patient is able to self-monitor and self-correct.