Definitions Impairment is a loss of function compared with a defined norm.
Disability arises when an impairment makes any task difficult or impossible to perform.
Handicap is evident when the individual wishes to perform that task. A significant proportion of the population has impairments which reduce their ability to effectively use standard consumer products, such as the telephone. The impairment groups described in this booklet have been defined in terms of their functional ability, or lack of it, and how this relates to the use of telephones. The proportion of the population with impairments increases with age. Hearing impairment - moderate .