One of the most profound differences between hearing-impaired and normal-hearing children is the rate of vocabulary acquisition. Typically developing children with normal hearing can learn more than 2 new words per day and have a vocabulary of 4,000-5,000 words by age 5. This is in stark contrast to the child with significant hearing loss who may have a vocabulary as small as 500 words at age 5 (Bloom, 2000;Conrad, 1979). These deficits in vocabulary acquisition will impact development of higher level language abilities including syntax, word segmentation and ultimately reading comprehension. Understanding and ameliorating deficits in vocabulary size can not only lead to improved word recognition but can also accelerate the acquisition of other linguistic competencies that are essential for communicative and academic success.
Specific Aim 1 will determine the sensory, perceptual, and cognitive factors that mediate vocabulary acquisition in hearing impaired (50 children age 6-7 years with cochlear implants or digital hearing aids;50 normal hearing age mates will be compared on all measures). Hypotheses to be tested (D1.1-D1.3) are based on the idea that receptive vocabulary in hearing-impaired children requires the efficient operation and integration of sensory, perceptual, and cognitive abilities. Hearing impaired children's ability to perceive speech in every day environments (background noise and at all levels of speech from soft to loud) facilitates the child's ability to """"""""overhear"""""""" language and promotes increased receptive vocabulary size through novel word learning (implicit learning). The less proficient a child is in perceiving speech in demanding listening conditions the more difficulty he/she will exhibit retaining information in working memory. Shortened memory span will influence explicit verbal learning and contribute to delayed vocabulary acquisition as measured by receptive vocabulary size. Hypotheses (D2.1 &D2.2) for Specific Aim 2 will address the variability in rate of language growth in children that have received early identification and device use by obtaining longitudinal data examining the long-term effects of speech perception and developing cognitive skills on vocabulary size. This study will use an integrated multidisciplinary approach to examine the interaction between perceptual and cognitive mechanisms in understanding and improving the linguistic skills of hearing impaired children.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Mentored Patient-Oriented Research Career Development Award (K23)
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Communication Disorders Review Committee (CDRC)
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Sklare, Dan
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Washington University
Schools of Medicine
Saint Louis
United States
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Davidson, Lisa S; Firszt, Jill B; Brenner, Chris et al. (2015) Evaluation of hearing aid frequency response fittings in pediatric and young adult bimodal recipients. J Am Acad Audiol 26:393-407
Davidson, Lisa S; Geers, Ann E; Nicholas, Johanna G (2014) The effects of audibility and novel word learning ability on vocabulary level in children with cochlear implants. Cochlear Implants Int 15:211-21
Geers, Ann E; Davidson, Lisa S; Uchanski, Rosalie M et al. (2013) Interdependence of linguistic and indexical speech perception skills in school-age children with early cochlear implantation. Ear Hear 34:562-74
Robinson, Elizabeth J; Davidson, Lisa S; Uchanski, Rosalie M et al. (2012) A longitudinal study of speech perception skills and device characteristics of adolescent cochlear implant users. J Am Acad Audiol 23:341-9
Davidson, Lisa S; Geers, Ann E; Blamey, Peter J et al. (2011) Factors contributing to speech perception scores in long-term pediatric cochlear implant users. Ear Hear 32:19S-26S
Davidson, Lisa S; Geers, Ann E; Brenner, Christine (2010) Cochlear implant characteristics and speech perception skills of adolescents with long-term device use. Otol Neurotol 31:1310-4