Producing speech sounds that are appropriate for age and dialect
Articulation involves the movement of the tongue, lips, jaw, and other speech organs (the articulators) to make speech sounds. Most children make some mistakes as they learn to say new words. Every sound has a different range of ages when the child should make the sound correctly. Infants begin to distinguish speech sounds from other sounds that they hear (like the vacuum cleaner) during the first month of life. As their oral structures grow and motor skills develop during the first year, babies begin to produce speech sounds beginning with cooing (vowel-like sounds) to more complex babbling (consonant and vowel sounds). Between 12 to 18 months, children say their first words. These words are usually simple consonant-vowel combinations such as ma, pa, nana (banana), wawa (water), and baba (bottle). By 2 years of age, toddlers have acquired about 50 words and are well on their way to learning the speech sound system of their native language. There is a developmental sequence of speech sound acquisition with sounds that are more easily produced and more frequent in the language mastered first. Early sounds are m, b, y, n, w, d, p, and h. Next sounds learned are t, ng, k, g, f, v, ch and j. Later developing sounds are sh, th, s, z, l and r.
It is not unusual for a 5 or 6 year old child to make a "w" sound for an "r" sound (e.g., "wabbit" for "rabbit"), an "f" sound for a "th" sound (e.g., "toof" for "tooth"), or produce the s and z sounds with a slight lisp.
An articulation disorder is diagnosed if the speech sound errors occur past the expected age for correct production. Sounds can be substituted, distorted, left off, added or changed. Some children with articulation disorders produce multiple articulation errors or distort sounds to such a degree that they are unintelligible.
Another type of speech sound disorder is a phonological disorder that involves patterns of sound errors. An example is a pattern called fronting. This occurs when children produce "t" and "d" for "k" and "g" as in "tiss" for "kiss" or "das" for "gas".
It is important for every child with speech sound difficulties to have a comprehensive evaluation performed by a licensed and certified speech language pathologist to determine the specific problems that the child has and to develop an appropriate therapy plan to remediate these difficulties.