DISCLAIMER: This website contains documents with terms that may be considered by today's reader as outdated and even offensive. For example, the term "hearing impairment" is sometimes used as a category for levels of hearing loss, such as hard of hearing and deaf. Some people now see cultural identification and communication preference as defining characteristics behind terms such as hard of hearing and deaf, and they do not favor terms conveying medical distinctions and loss. Yet we recognize that removing and changing terms may alter the precise meaning of the scientific author. A solution may be found by expanding the scope of future research to include non-medical perspectives.