Infants who are deaf or hard of hearing go through critical sensitive periods for the development of vocabulary, grammar and the sounds of spoken English, according to a University of Colorado at Boulder professor. Christine Yoshinaga-Itano, chair of the speech, language and hearing sciences department, presented "What the deaf child can't afford to miss: Language, Deafness and the Remarkable Infant" Feb. 17 at the annual meeting of the American Association for the Advancement of Science.