How Children Acquire Speech Sounds: Normal, Delayed and Disordered Development
Ralph L. Shelton, Ph.D., CCC-SLP
Many parents notice that their children do not use certain speech sounds or use fewer speech sounds correctly than their playmates. The children’s speech may be difficult to understand. Is this reason for concern, or will they catch up? Children developing speech normally do so at different rates.
Development of Articulation
Children’s development of spoken language follows an orderly sequence. In the first year of life infant cough and burp, “ooh” and “aah”, and babble vowels and consonants. In doing so they learn to control their speech mechanism and so move toward use of speech sound and words.
Speech sounds are acquired in an orderly sequence through about the seventh or eighth year. Vowels are acquired earlier than consonants and are less likely to be misarticulated.
Consonants fall into classes defined by how they are produced, where in the mouth they are produced, and whether or not they are produced with “voice.” The early developing consonants tend to be nasal sounds that go out of the nose (m, n, ing), sounds made with a gliding motion (w, j), and stops. The stops (p, b, t, d, k, g) are “popping sounds.” They are made in a similar fashion but at different locations in the mouth. Each one requires that air pressure be built up in the mouth and then released quickly. Fricatives (f, s, v, z, sh), affricates (ch, dj as in jeep), and liquids (r, l) appear later. The fricatives require that air be blown through a narrow opening. Fricative sounds differ from one another in where the openings are located and in the shape of the openings.
Sounds made with the tongue tip tend to be acquired later than sounds made with the lips or with the lips and teeth. The sounds most likely to be misarticulated by school-age children are /s/, /r/ and /l/. As new speech sounds are first acquired, their production is inconsistent. For example, some of the first /p/ sounds may be correct and some may be misarticulated. Over time, the way sounds are produced becomes more consistent.
Phonological patterns are the simplified versions o adult speech that children use when they are learning and developing speech.
||Consonants are deleted from clusters. The /st/ in stop becomes /t/, and stop becomes top.
|Final consonant deletion
||Consonants are deleted from the ends of words or syllables. Hat becomes hae.
||Stops such as /p, t/, and /k/ replace fricatives such as /f, s/, and /sh/. Sun becomes tun.
||The liquids /r/ and /l/ are replaced by glides. Right becomes wight.
||Vowels replace /l/ and some forms of /r/. Yellow becomes yewow.
|Unstressed syllable deletion
||Weak syllables are omitted. Banana becomes nana.
Sounds are produced more forward in the mouth. Key becomes tey, show becomes sue.
Sound System Delay and Disorder
Many speech errors are common early in a child’s development and are not a problem unless they persist for too long a time. For example, young children just learning speech may place the tongue against or between the front teeth during the /s/ and /z/ sounds. The lisp occurs because the tongue is positioned height in the moth early on in life. As tongue position changes with growth, frontal lisping should stop.
Children who follow the usual sequence of sound development but at a slower rate are said to have delayed development of the sound system. These children misarticulate sounds that are used correctly by most other children their age. Many of these children continue using simplification patterns for too long.
When children show sound articulation or patterns that differ in kind from those seen in most children, they are said to have disordered sound systems. Lateral lisps, where the air stream is directed over one or both sides of the tongue are not a part of normal development and so are classified as disordered speech. Lateral lisps tend to persist unless the child is taught correct articulation. Another distortion that is not part of normal development involves nasalized speech. Nasal escape of air and sounds is often associated with cleft palate and related conditions which may require medical treatment.
Unusual phonological patterns may be classified as disordered. One example is the addition of extra syllables at the end of words. The added syllable, perhaps um, could serve to indicate past tense.
The distinction between sound system delay and disorder is not sharp, and the two may occur together. Delays probably occur more frequently than disorders. Sound system disorders and delays that are not associated with structural or neurogenic impairment and that are not severe tend to improve spontaneously over time. If the problem is more severe, direct intervention may be warranted.