What is a Speech Disorder?
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. By the time a child is 48 months old, however, she should be speaking well enough to be understood all of the time. See Speech and Language Milestones Checklists. 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. See Speech and Language Milestones Checklists. 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.
Not to be confused with developmental speech delay, is developmental apraxia or (dyspraxia). This is a condition which affects the child’s ability to plan, sequence and execute the movements necessary for speech. The child may also have difficulty receiving sensory feedback regarding the placement of the articulators for speech.