Dr. Johnston of Johns Hopkins University School of Medicine and Chief Medical Officer at Kennedy Krieger Institute has no relevant financial relationships to disclose.)
This article includes discussion of disorders of articulation, articulation disorders, motor speech disorders, and speech sound disorders. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Disorders of articulation generally refers to common childhood speech problems. These disorders are now more commonly referred to as speech sound disorders. They are generally treated by speech-language pathologists. Awareness of disorders of articulation aids physicians in effective identification and referrals. This article reviews these common disorders, includes an understanding of current genetic underpinnings, touches on nondevelopmental and degenerative causes of articulation difficulties, and provides an overview of the current intervention debate.
• Disorders of articulation are common in early childhood and are generally resolved by adolescence, although associated language and reading difficulties may persist.
• Disorders of articulation manifest in the form of incorrect pronunciation, particularly of consonants.
• Some genetic syndromes and neurodevelopmental disabilities are associated with disorders of articulation. There are also anatomic and neurologic causes of nondevelopmental articulation disorders. Other common causes of articulation disorders in adults are degenerative diseases that affect oral motor muscles.
• Treatment varies and determining evidenced-based practices is an active area of research.
Historical note and terminology
Demosthenes, the Greek orator, had difficulties with articulation in his youth and pioneered speech therapy by placing pebbles underneath his tongue to elevate it. Aristotle recognized that articulation, the organized combination of consonants and vowels, is required for human speech. In 1848, Bouillaud listed the components required for spoken language as the instruments, such as the tongue, which provide “articulatory power,” and the “cerebral organ,” which coordinates speech.
The functional outcome of disorders of articulation is impaired intelligibility; however, a number of disorders can result in speech being difficult to understand. Dysarthria refers to acquired or congenital neurologic motor speech impairment characterized by slow, weak, uncoordinated movements of the speech musculature and can affect many areas required for speech production including articulation, but also respiration, phonation, and prosody (Enderby 2013). The term “phonological disorder” is sometimes used interchangeably with “disorders of articulation;” however, the American Speech-Language-Hearing Association distinguishes phonological disorder as the characteristic confusion of certain patterns of sounds, as opposed to the inability to produce certain sounds. Articulation disorder emphasizes that speech is a motor activity. Phonological disorder emphasizes that speech requires knowledge of language patterns (Bleile 1995).
Childhood apraxia of speech is controversial, and is defined by the American Speech-Language-Hearing Association's position statement as “a neurologic childhood (pediatric) speech sound disorder in which precision and consistency of movements underlying speech are impaired in the absence of neuromuscular deficits.” A survey of speech-language pathologists revealed little agreement on its diagnostic criteria despite its frequent diagnosis and treatment (Forrest 2003). The term speech sound disorders as defined by the International Expert Panel on Multilingual Children's Speech includes “any combination of difficulties with perception, articulation/motor production and/or phonological representation of speech segments (consonants and vowels), phonotactics (syllable and word shapes), and prosody (lexical and grammatical tones, rhythm, stress, and intonation) that may impact speech intelligibility and acceptability” (International Expert Panel on Multilingual Children's Speech). Therefore, speech sound disorders can refer to difficulty with articulation, phonology, motor speech, or childhood apraxia of speech (McLeod et al 2013a).
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