The limited epidemiologic data that are available suggest that prevalence is slightly higher in boys than girls, and has a low positive correlation with socioeconomic status.
Speech sound disorder refers to any combination of difficulties with perception, motor production, and/or the phonological representation of speech sounds and speech segments that impact speech intelligibility. The disorder is characterized by:
- Persistent difficulty with speech sound production that interferes with speech intelligibility or prevents verbal communication of messages
- Limitations in effective communication that interfere with social participation, academic achievement, or occupational performance, individually or any combination.
Speech sound disorders can impact the form of speech sounds or the function of speech sounds within a language. Adults with speech production difficulties may experience trouble with phonological knowledge of speech sounds or the ability to coordinate movements of the articulator (i.e, the jaw, tongue, and lips), with breathing and vocalizing for speech. A speech sound disorder is diagnosed when speech sound production is not what would be expected based on the child’s age and developmental stage and when the deficits are not a result of a physical, structural, neurological, or hearing impairment.
Signs and symptoms of speech sound disorders include:
- Omissions/deletions—certain sounds are omitted or deleted (e.g., "cu" for "cup")
- Substitutions—one or more sounds are substituted (e.g., "wabbit" for "rabbit")
- Additions—one or more extra sounds are added or inserted into a word (e.g., "buhlack" for "black")
- Distortions—sounds are altered or changed (e.g., a lateral "s")
- Whole-word/syllable-level errors—weak syllables are deleted (e.g., "tephone" for "telephone") or a syllable is repeated or deleted (e.g., "dada" for "dad")
- Prosody errors—errors occur in stress, intensity, rhythm, and intonation.
Not all sound substitutions and omissions are speech errors. Instead, they may be related to a feature of a speaker's dialect or accent. Any regional, social or cultural/ethnic variations should be taken into account before considering a diagnosis.