Speech is the verbal means of communicating. Speech consists of articulation, voice, and fluency. Articulation refers to how we make speech sounds with our mouth (e.g., a child must learn how to make the "g" sound in order to say "gum" instead of "dum"). Voice uses breathing and the vocal folds to generate sound. Fluency is the rhythm of speech. A person is said to have a speech disorder if he or she is unable to produce correct speech sounds, speak in a fluent manner, or use their voice correctly.
An articulation disorder may be diagnosed in a child when he or she demonstrates difficulty with specific speech sounds, beyond that of normal developmental speech issues. The following etiologies may result in articulation disorder: developmental delay, hearing impairment, autism, birth defect or brain injury, as well as other etiologies.
An articulation test may be used to diagnose an articulation disorder. During an articulation test, the sound errors occurring in a person's speech are documented and scored. An examination of the face and mouth may also be completed to assess the function of speech-related muscles.
Adults may demonstrate articulation problems as a result of a stroke or injury to the head or due to speech issues from childhood.
Apraxia is a type of articulation disorder in which the brain has difficulty planning the sequence of mouth movements necessary to create sounds, syllables, and words. Apraxia can occur in children, this is known as CAS or childhood apraxia of speech. Adults can also develop apraxia as a result of brain damage from strokes or other neurologic insults.
Dysarthria is another disorder of articulation in which the muscles used for speech are weak or difficult to control. It is often characterized by slurred or slow speech that can be difficult to understand. Dysarthria can occur in both children and adults. It can be caused by neurological disorders, conditions that cause facial paralysis or effects of medications.
"Dysarthria." - Mayo Clinic. Accessed April 29, 2015. http://www.mayoclinic.org/diseases-conditions/dysarthria/basics/definition/con-20035008.
"Childhood Apraxia of Speech." Childhood Apraxia of Speech. Accessed April 29, 2015. http://www.asha.org/public/speech/disorders/ChildhoodApraxia/.