Down Syndrome Research and Practice Volume 3 Number 3 Pages 75-91

Twenty-six adolescents and young adults with Down’s syndrome and 26 IQand CA-matched youth with other causes of intellectual impairment (comparison group) repeated a battery of audiological and auditory-cognitive tests on three annual assessments. Audiological tests revealed the following differences between the group with Down’s syndrome and the comparison group: a) Poorer acuity and longitudinal declines at each frequency from 250-8000 Hz for the group with Down’s syndrome, particularly at the highest frequencies; b) A tendency for the middle ear problems of Down's syndrome individuals to be bilateral, chronic, and to reflect no mobility, retraction, or reduced mobility of the tympanic membrane; and c) Poorer reception and discrimination of speech in the group with Down’s syndrome. Correlational analyses revealed the following reliable relationships between performance on audiological and auditory-cognitive tests: a) individuals with Down’s syndrome who had lower speech discrimination scores, poorer acoustic reflexes, or bilaterally impaired tympanograms repeated spoken sentences less accurately; b) individuals with Down’s syndrome who had lower speech discrimination scores performed more poorly on a language comprehension task; and c) individuals with Down’s syndrome with impaired hearing (regardless of how it was measured) identified fewer spoken words when the words were rapidly followed by a masking noise or made discriminable by brief consonant sounds. It was suggested that poorer performance by hearing-impaired subjects with Down’s syndrome on auditory-cognitive tasks may have been due to an interaction of lower auditory acuity and slower processing speed. Also, because relationships between hearing and cognitive variables were not present in the comparison group, it was tentatively suggested that hearing loss may be more detrimental to cognitive abilities in intellectually impaired individuals with Down’s syndrome. Introduction One well-established fact about the perceptual capabilities of the population with Down’s syndrome is its high rate of hearing problems (e.g., Cunningham and McArthur, 1981; Downs, 1983; Evenhuis, van Zanten, Brocaar and Roerdinkholder, 1992; van Gorp and Baker, 1984; Keiser, Montague, Wold, Maune and Pattison, 1981; Schwartz and Schwartz, 1978; Wilson, Folsom and Widen, 1983). An important empirical question that has not been widely addressed, however, is whether Down's syndrome hearing problems are characteristic of individuals with Down’s syndrome or, instead, individuals who are moderately intellectually impaired. Only a few studies of Down’s syndrome hearing ability have included an intellectually impaired comparison group (Brooks, Wooley and Kanjilal, 1972; Buchanan, 1990), and only one study, to our knowledge, has included an intellectually impaired comparison group matched on both IQ and CA (Dahle and McCollister, 1986). Dahle and McCollister (1986) found that children with Down’s syndrome have a significantly higher prevalence of hearing and otologic disorders than their matched peers. A central question addressed in the present study is whether adolescents and adults with Down’s syndrome have poorer hearing abilities than same-age, equally-intelligent intellectually disabled peers.