30 Chapter 2
Children acquire the sounds and phonology of the language to which they are exposed. For
example, children reared by Navajo, Hopi, Japa nese, or Spanish speakers learn the speech sounds
and phonology of those languages. Children born deaf do not normally acquire any true speech
sounds or phonology because they are deprived of the auditory exposure required to learn them.
These children have undifferentiated and differentiated crying and cooing and begin the babbling
stage at the same time as hearing children. However, without special intervention or therapies,
children who are deaf do not pro gress beyond this stage and learn speech. Of course, the age at
which a child loses his or her hearing is impor tant in determining what level of articulation and
phonology intervention is necessary. An older child with hearing loss will have heard speech
sounds and will prob ably have learned them.
The effect of partial hearing loss on articulation and phonological development also depends
on the age when it occurs. Similar to a child who is deaf, a child who loses his or her hearing before
the age of approximately 7 or 8 years may have been exposed to the auditory stimulation neces-
sary to learn speech sounds and phonology. Infants born hard- of- hearing have greater difficulty
learning the phonemes and phonological structures of language than children who lose their
hearing later in life. In addition, the frequency of the hearing loss must be considered. Some hear-
ing disorders primarily involve the higher, middle, or lower frequency ranges, causing par tic u lar
phonemes to be more distorted. For example, a child with a prominently high- frequency hearing
loss is likely to misarticulate speech sounds such as /s/, sh, and /z/ while mastering lower- frequency
speech sounds such as ah, /w/, and /l/.
Any defect, malformation, deformity, or irregularity of the oral structures can impair articula-
tion. These structural abnormalities impair or prohibit the excursion, contact, and mobility of the
articulators during speech. The severity of the articulatory disorders is usually related to the extent
of the structural defects.
Cleft lip and palate also affect articulation. In these congenital birth defects there is incomplete
fusion of the lips, palatal shelves, and velum. Consequently, the articulators may be impaired or
unable to create the airstream valving necessary for normal speech. Individuals with bilateral com-
plete clefts usually have more impaired articulation. Individuals with cleft palate and those with
dental and orthodontic impairments may also have prematurely missing or jumbled teeth, causing
the production of dental phonemes to be distorted.
Some individuals have disproportionately large or small tongues and/or palatal vaults that are
insufficient to house them properly. A disproportionately large tongue— macroglossia— occurs
more frequently in persons with Down syndrome, resulting in slowly produced, distorted speech.
Tongue reduction surgery is sometimes used to counter the effects of the macroglossia. A dispro-
portionately small tongue— microglossia—is rare but can also reduce the precision of speech. Also
rare is a shortened lingual frenulum, a cord of tissue running from the f loor of the mouth to the
middle of the underside of the tongue. In some children, the lingual frenulum may be too short to
give the tongue functional mobility, especially the necessary elevation for phonemes such as /t/, /d/,
and th. The lingual frenulum must be excised, or “clipped,” to permit proper mobility.
Other structural abnormalities include partial or complete glossectomy— surgical removal of
the tongue— usually because of oral cancer treatment. In automobile accidents and other high-
speed impacts, a victim may be thrust forward and bite off the tongue tip. Oral- facial anomalies
affecting the size and positioning of the mandible in relation to the maxilla may also result in
structural articulation disorders.