Types of Speech Disorders

One of the most commonly treated areas within our scope of practice as Speech-Language Pathologists is speech sound disorders. When a child has a speech sound disorder, they may have trouble saying certain sounds and words past the expected age, ultimately making it harder for others to understand them.

Research suggests that 2.3% to 24.6% of school-aged children may have speech delay or speech sound disorder. In a class of 25 students, that could be anywhere from one student per class, all the way up to 6 students per class! Even though speech sound disorders are highly common, many don’t realize that the term itself encompasses a variety of specific diagnoses. Articulation disorders, phonological disorders, and childhood apraxia of speech are three distinct types of speech sound disorders, and approach to treatment for each disorder can vary significantly.

Articulation Disorder

An articulation disorder involves difficulty producing specific speech sounds correctly. A child with an articulation disorder may substitute, omit, add, or distort individual sounds. For example, a child might say “wabbit” instead of “rabbit” or “thun” instead of “sun.” These errors are typically consistent and predictable — the child struggles with the same sound(s) regardless of where they appear in a word.

Treatment for articulation disorders typically involves direct practice with the target sound, starting in isolation, then moving to syllables, words, sentences, and eventually conversational speech. With consistent practice, most children make excellent progress.

Phonological Disorder

Unlike articulation disorders which involve individual sounds, phonological disorders involve patterns of errors that affect entire classes of sounds. For example, a child might replace all “back sounds” (like k and g) with “front sounds” (like t and d), saying “tat” for “cat” and “do” for “go.” These patterns, called phonological processes, are normal in very young children but should fade by certain ages.

Treatment for phonological disorders focuses on helping the child understand and internalize the sound patterns of their language, rather than drilling individual sounds. This approach can lead to rapid, widespread improvements across multiple sounds at once.

Childhood Apraxia of Speech (CAS)

Childhood apraxia of speech (CAS) is a motor speech disorder that affects the brain’s ability to plan and coordinate the precise movements needed for speech. Unlike articulation or phonological disorders, CAS is not about a child not knowing how to produce sounds — it’s about the brain having difficulty sending the right signals to the muscles used for speaking.

Children with CAS may exhibit inconsistent errors (saying the same word differently each time), difficulty with longer words or phrases, and unusual prosody (rhythm and intonation of speech). CAS requires specialized, intensive treatment that focuses on motor planning and repetitive practice of speech movements. Frequent therapy sessions are often recommended to maximize progress.