When a child has an articulation disorder, she is unable to coordinate her articulators in order to produce a specific sound clearly. If your child has an articulation disorder or delay, she has difficulty with the movements required by the articulators—lips, tongue, soft palate–to produce sound(s). As a result, another sound or a distortion of the attempted sound is produced instead.
Similarly, if your child has a phonological disorder or delay, she has difficulty with the patterns of speech sounds, or phonological processes, which are stored in the brain. All children use phonological processes as they develop speech in order to simplify speech sounds or combinations of sounds that they are not yet developmentally prepared to make. Each such phonological process is expected to disappear by a certain age. If a child continues to use a phonological process past the age of disappearance, she may have a phonological delay or disorder. A child with a phonological disorder or delay may be mispronouncing sounds in some words but not in others (e.g. she may say “ca” for “cat” because she omits the final sounds of words, even though she can say the sound /t/ just fine in “toy”).
When should I seek out help?
Although some children are precocious in the acquisition of speech and may be able to produce understandable speech by the time they are 30 months of age, in some children, it is not uncommon for one or two speech sounds to remain “unlearned” until 72 months of age. Children are expected to be intelligible to all adults (familiar and unfamiliar) by the time they’re 48 months. If a child’s overall speech intelligibility is reduced for his/her age (i.e., less than 50% intelligible to unfamiliar adults by age 36 months and less than 100% intelligible by 48 months even with the presence of some continuing phonological processes), then s/he may also have a phonological delay or disorder (Bleile, 1995).
As the child matures from the babbling baby to the competent speaker, she eliminates from her speech the babbled sounds which are not common to her environment, making judgments based on listener feedback to select patterns of speech which are continually fine tuned and eventually generalized. The child unwittingly learns to pair, and then group, speech sounds which share characteristics. For example, /t/ and /d/ are paired because they are both produced when the tongue tip strikes the hard palate behind the teeth and produces a little explosion of air. Though made in the back of the mouth with the soft palate raised to strike the back throat wall, /k/ and /g/ are grouped with /t/ and /d/ because of the explosion of air resulting when they are made. Besides such groupings of speech sounds, the child also learns that words have shapes made of consonant and vowel sounds and these sounds are patterned in certain ways.
The acquisition of speech occurs the same way for children all over the world, and at each chronological age along the developmental continuum, one can predict what developmental features should be present. A fourteen-month-old child, for example, may produce [naena] for banana, while the two-year-old child may say [baena], and the three-year-old child may finally say banana. The process of developing speech, called developmental phonology, may be slower than expected, arrested, or idiosyncratic, all of which would be considered a developmental speech disorder/delay. Our Speech and Language Milestones Checklists can help you determine what speech sounds are typically expected for children of various ages.
How does speech therapy help?
First, a speech therapist helps your child hear the difference between the sound that she is making and the target sound. Then the therapist supports your child in knowing how to use her lips, jaw, and tongue to make the target sound. A child practices saying the target sound in isolation, in words, in phrases, in sentences, and, finally in connected speech across communication partners and across settings.
What if my child speaks more than one language?
For bilingual children who speak English as their second language, it is important to discern whether a sound they produce in error is indeed in the sound repertoire of the second language. For example, there is no “th” sound in the Spanish, Russian, and Hebrew languages. In such a case, the child’s mispronunciation would be considered a product of accent and not a speech disorder.
Bleile, K.M. (1995). Manual of Articulation and Phonological Disorders: Infancy Through Adulthood. San Diego, CA: Singular Publishing Group, Inc.