Estimating the vocabulary size of the disadvantaged reader

Vocabulary is an important factor in reading comprehension. Assessing the vocabulary range of the audience for an engineering document is not an easy task ordinarily, and is even more difficult when the audience includes disadvantaged readers. This report supports the hypothesis that the less often a word appears in print, the less likely it is to be known by a reader. A test was given to 277 hearing students ranging in age from 9 through 14, and the same test was also given to 438 hearing-impaired students ranging in age from 10 to 19, including the special case of college freshmen. Results showed that prelingually deaf students trailed far behind their hearing peers, e.g. hearing subjects knew 63 percent of the words up to the 24,000th word, while hearing-impaired subjects knew only 62 percent of the words up to the 2000th word.