5 - Deafness and language development

Summary

The major purpose of this chapter is to discuss the effects of deafness on the development of English. The language development of deaf children is considered in relation to the type of input to which they are exposed in infancy and early childhood, namely, Oral English, Manually Coded English, or American Sign Language. Also discussed is the contention that the language acquisition process of some deaf children should be viewed from either a bilingual or an English-as-a-second-language (ESL) framework. A representative, rather than exhaustive, sample of research regarding these issues is presented, and some conclusions are inferred from the evidence.

Definition of deafness

To depict the effects of deafness on English language development, it is important to define the population under consideration (Quigley & Kretschmer, 1982). Typically, the ability to hear is measured in decibels (dB) across a range of frequencies from 125 to 8000 hertz (Hz). The degree of an individual's hearing impairment (i.e., hearing threshold level) is represented on the audiogram as the average loss across the speech frequencies (500, 1000, and 2000 Hz). Five categories of hearing impairment have been established and are illustrated in Table 1. It can be seen that hearing impairment is a generic term representing all degrees of hearing loss, with deafness corresponding to the extreme or profound category of impairment. An individual is considered deaf if hearing impairment is so great that vision, rather than audition, becomes the major link to receptive language development.