Speech Sound Disorders
What is Speech
Speech is our verbal means of communicating. Speech consists of the following:
- Articulation- how speech sounds are made (e.g., children must learn how to produce the "r" sound in order to say "rabbit" instead of "wabbit")
- Fluency- the rhythm of speech (e.g., hesitations or stuttering can affect fluency)
Based on research in the area of speech development, children are expected to develop and produce speech sounds by a specific age to be considered within normal limits. For example, the speech sounds /b/, /p/, /m/, /d/, and /k/ are typically expected to develop by three years of age. While speech sounds may develop slightly differently for all children, if a child has not developed age-appropriate sounds by the expected age they are considered to have a speech delay. Speech delay is characterized by reduced intelligibility and increased risk for broader communication and academic difficulties. Possible causes include: genetics, early history of recurrent ear infections, motor speech involvement associated with either developmental apraxia of speech or with mild dysarthria, and developmental cognitive involvement.
An articulation disorder involves difficulty making sounds. Sounds can be substituted, left off, added, or changed. These errors may make it hard for people to understand a child’s message. 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.
Phonological Process Disorders
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 example is cluster reduction, which involves words starting with two consonants, such as broken or spoon. When children use only one of the sounds (e.g., "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.
Dysarthria in Children
Dysarthria is a neurogenic speech disorder that results in weakness, slowness, and/or incoordination of the muscles of respiration, phonation, articulation, resonance and feeding. Because the child has under-responsive muscles, feeding skills are compromised and the child is at risk for aspiration and choking. Additionally, the poorly functioning muscles lead to unintelligible speech.
Childhood Apraxia of Speech (CAS)
CAS, or verbal dyspraxia/apraxia, is a neuromotor articulatory speech disorder that interferes with a child's ability to correctly pronounce sounds, syllables and words. A child with CAS cannot consistently move his or her face, tongue, lips and jaw into the correct position to make speech sounds or produce syllables or words. Speech produced by an individual with CAS is often marked by inconsistent productions of the same sound or word (e.g., a child attempting to say the word “dog” three times produces the following: “ka”, “dog”, “ga”).
Stuttering is a fluency disorder characterized by an interruption in the smooth flow of speech. Several different causes are believed to contribute to the development of stuttering:
- Genetics- approximately 60% of individuals who stutter have a family member who also stutters
- Development- children with other speech and language problems or developmental delays are more likely to stutter
- Family dynamics- increased expectations and fast-paced lifestyles can contribute to stuttering
- Neurophysiology- research has shown that people who stutter process speech and language in different areas of the brain than those who do not stutter
Stuttering affects approximately 1% of the population, and affects males versus females at a ratio of 4:1.