Essay: Down syndrome

Introduction
Down syndrome is the most common genetic disordered that causes developmental delay. Children with Down syndrome are very social, however, in some case it is difficult to communicate with them as most people cannot understand their speech. Researches about phonological system in children with Down syndrome were increased to understand the deficits in order to improve their receptive and expressive language. The following article is about the phonological development in children with Down syndrome and intervening strategies (Gammon, 2001).This study is about the phonological development in children with Down syndrome and the intervention strategies. It is divided into two main parts; the first one is about the factors that affect the phonological development in these children. The second part is dealing with prelinguistic stage, the transition to speech, the phonology of the single words, phonological characteristics of conversation, speech intelligibility
Summary:
There are many factors that affect the phonological development in children with Down syndrome. These factors are different in severity from one child to another. These factors include the cognitive deficit, hearing loss, differences in anatomy, and language environment. The first factor which is the hearing loss, children with Down syndrome usually suffer from hearing loss in one or both ears. Downs (1980) reported that 78% of the children she tested were found to have “hearing problems” in one or both ears. Hearing loss affect the language acquisition in these children. Therefore, hearing assessment is important to treat hearing loss as an intervention strategy. The second factor affects Down syndrome phonological system is the differences in anatomy and physiology. Children with Down syndrome have similar features such as small mouth, the deficient in the facial and tongue muscles, muscle weakness, and protruded tongue. All these features affect the pronunciation of both consonant and vowels. In terms of intervention in this domain, Yarter (1980) suggested physiotherapy and exercises to improve speech-motor deficits related to hypotonicity . Kumin, Councill and Goodman (1994) suggested strengthening the orofacial musculature through a program of lip massage. The third factor is the language input the child received from his parents and caregiver. Parents and caregivers should increase this type of input.
The second part of the study provides four aspects of Down syndrome phonology. The first aspect is the prelinguistic vocal development. Investigations of prelinguistic development suggests that infants with Down syndrome are nearly typical in this domain. Both cross-sectional and longitudinal studies have documented strong similarities in the amount of vocalization produced; in the developmental timetable, particularly age at onset of canonical babble; and in the characteristics of consonants and vowels occurring in canonical babble (Dodd, 1972; Oller & Seibert, 1988; B.L. Smith & Oller, 1981; B.L. Smith & Stoel-Gammon 1996; Steffens, Oller, Lynch & Urbano, 1992)
The average age of onset of canonical babbling among the infants with Down syndrome was about 9 months, approximately two months later than the age for the typically developing infants. Because hypotonicity and delays in motor development are characteristic of Down syndrome, the relative instability in canonical babbling may be a consequence of deficits in the motor domain.
The second aspect is the transition to speech. According to the typical developmental timetable, children’s first words generally appear around the end of the first year and overlap with canonical babble for a period of 6-8 months. In a longitudinal study of typically developing infants, Robb, Bauer, and Tyler (1994) reported that when their subjects had a productive vocabulary of about 10 different words, the proportion of words and babble in their spontaneous productions was roughly equal. When the productive vocabulary reached 50 words, at around 18 months of age, the ratio of words to babble was about three to one.
During the transition to speech, the phonetic characteristics of babble and speech are highly similar (Locke, 1983; Stoel-Gammon, 1998). Specifically, the types of consonants that occur most frequently in late babbling, namely, stops, nasals and glides, also predominate in early word productions, while the consonants that are infrequent in babble, liquids, fricatives, and affricates, are precisely those that appear later in the acquisition of meaningful speech (Stoel-Gammon, 1985). Moreover, the consonant-vowel syllable structure which is characteristic of the canonical babbling period is also the most frequent syllabic type in early word productions. Thus, among the typically developing population, babbling and early speech share the same basic phonetic properties in terms of sound types and syllable shapes.
In general, increased use of complex babble in the prelinguistic period is linked to better performance on the speech and language measures after the onset of speech and in the years that follow. These findings suggest that babbling serves as a foundation for the acquisition of speech and language;
Most children with Down syndrome exhibit a substantial delay in the appearance of first words, in spite of their normal babbling patterns.
Taken together, the research by Buckley and B.L. Smith indicates that the onset of meaningful speech is significantly delayed in the infants with Down syndrome and that after the appearance of words, growth of productive vocabulary is exceedingly slow. Other investigations of lexical acquisition in children with Down syndrome have shown that even when the Down syndrome group is matched to a typically developing control group on mental (rather than chronological) age, lexical acquisition in children with Down syndrome is delayed (Chapman, 1997).
In terms of intervention strategies appropriate for the transition to speech, the focus should be on supporting lexical acquisition by increasing the child’s awareness of the use of sounds as meaningful elements in communication. Specifically, caregivers (i.e. parents, child-care workers, teachers) should encourage the use of words by producing phonetically contingent responses to non-meaningful vocalisations; for example, caregivers might repeat the child’s non meaningful utterance [ba] and link it to the phonetically similar word “ball”, thus increasing the likelihood of [ba] being used as a meaningful utterance. In addition, caregivers can play “sound games” to make infants and toddlers aware of speech sounds and of sound-meaning relationships with the goal of increasing the child’s repertoire of speech sounds and syllable shapes.
The phonology of single words
In general, word productions of children with Down syndrome have the same phonological characteristics as those of children with typical development (Dodd & Leahy, 1989; Rosenberg & Abbeduto, 1993). In particular, stop, nasal and glide consonants tend to be produced accurately while fricatives, affricates and liquids are often in error (Bleile & Schwarz, 1984; B.L. Smith, 1984; Stoel-Gammon, 1980, 1981).
As might be expected, however, phonological acquisition in children with Down syndrome proceeds more slowly than in their cognitively typical peers. B.L. Smith and Stoel-Gammon (1983) calculated the rate of suppression of four phonological processes in their longitudinal study. Errors documented for young children with Down syndrome tend to persist through adolescence and even adulthood .Dodd (1975; 1976) suggested that these errors are related toa general deficit in their motor abilities.
In terms of intervention for single-word productions, most programs focus on increasing the phonetic repertoire and reducing the number of errors, using therapy techniques similar to those for children with phonological delay or disorder.
Speech intelligibility
At the age four years, the speech of most children with typical development is fully intelligible, even though their phonological systems are not yet complete (Coplan & Gleason, 1988). By comparison, the speech of some individuals with Down syndrome tends to be unintelligible throughout their lives even though their mental age may exceed four years (Kumin 1994; Pueschel & Hopman, 1993; Rosin, Swift, Bless & Vetter, 1988; Shriberg & Widder, 1990). Long-standing difficulties with intelligibility can presumably be attributed to phonological patterns associated with Down syndrome.
There are few intervention programs for children with Down syndrome aimed specifically at increasing intelligibility (but see Swift & Rosin, 1990), and treatment for language, at least in the United States, is often part of more general educational programs designed to teach “life skills”. The ultimate goal of such programs is to allow individuals with learning disabilities to live independently and work in the community. In the domain of speech and language, efforts are often directed toward increasing the functional communication skills necessary for social interactions and vocational training with little emphasis on phonology skills per se.