The researchers investigated the effects of adult language input on the quantity of language, vocabulary development, and understanding of basic concepts of deaf and hard of hearing (DHH) children who used listening and spoken language. Using audio recording and Language ENvironment Analysis (LENA) software, the study involved 30 preschool DHH children who used spoken language as their communication modality and 11 typically hearing same-age peers. The children's language and the language spoken to them during all waking hours over a 2-day period (16 hours per day) were recorded and analyzed quantitatively and were compared to the children's performance on the Boehm Test of Basic Concepts and the Peabody Picture Vocabulary Test. The results highlight the relationship between the quantity of adult language and the language, vocabulary, and basic concept knowledge of DHH preschool children who use listening and spoken language.