According to the Canadian Association of the Deaf (CAD) ‘Deafness’  is medically defined by the extent of loss of functional hearing and by dependence upon visual communication.

It recognizes a person to be medically/audiologically deaf when that person has little or no functional hearing and depends upon visual rather than auditory communication. “Visual means of communication” include Sign language, lipreading, speech-reading, and reading and writing. “Auditory means of communication” include voice, hearing, and hearing aids and devices.

The CAD also accepts the definition developed by Gallaudet University in the United States: “Anyone who cannot understand speech (with or without hearing aids or other devices) using sound alone (i.e. no visual cues such as lipreading) is deaf.”

A commonly-used definition of deafness is the inability to “fully acquire spoken linguistic skills through [the] auditory channel, aided or unaided” (J. Woodward, “Implications for socio-linguistics research among the Deaf”, Sign Language Studies, 1972). The CAD rejects this definition because it excludes all post-lingually deafened persons

They also reject the definition, once common in government programs, that a person is deaf or hard of hearing based on his/her ability to hear another person with whom he/she is familiar, in a quiet setting. Our lives are not lived in quiet settings, and persons already familiar to us are not the only persons we must deal with in our everyday lives. There is no legitimacy in a definition that measures our deafness by our ability to hear Mommy speaking quietly in the family kitchen!

Any realistic definition of deafness must give consideration to environmental noises. In a quiet room with one or two other persons present, many hard of hearing persons can function quite well with a hearing-aid. When any kind of noise such as traffic, air-conditioning, or numerous other people enter the situation, however, the hard of hearing person who does not have Sign language can in effect become deaf. This example demonstrates that hearing loss per se cannot be used as the sole factor or as a “stand-alone” factor in defining deafness.

The Deaf, the deafened, and the hard of hearing are all very distinct groups. Using the proper terminology shows respect for their differences.

deaf:
A medical/audiological term referring to those people who have little or no functional hearing. May also be used as a collective noun (“the deaf”) to refer to people who are medically deaf but who do not necessarily identify with the Deaf community.

Deaf (with capital D):
A sociological term referring to those individuals who are medically deaf or hard of hearing who identify with and participate in the culture, society, and language of Deaf people, which is based on Sign language. Their preferred mode of communication is Sign.

deafened (Also known as late-deafened.): (This is where I fit in)
This is both a medical and a sociological term referring to individuals who have become deaf later in life and who may not be able to identify with either the Deaf or the hard of hearing communities.

hard of hearing:
A person whose hearing loss ranges from mild to profound and whose usual means of communication is speech. It is both a medical and a sociological term.

hearing impaired:
This term is not acceptable in referring to people with a hearing loss. It should never be used in referring to Deaf people. “Hearing impaired” is a medical condition; it is not a collective noun for people who have varying degrees of hearing loss. It fails to recognize the differences between the Deaf and the hard of hearing communities.

person who is deaf :
Acceptable but overly sensitive substitute for “deaf”.

manual deaf, Signing deaf:
A deaf person whose preferred mode of communication is Sign language.

oral deaf:
A deaf person whose preferred mode of communication is verbal and auditory and/or lipreading. An oral deaf person who can both Sign and speak can be considered “Deaf” if he/she is accepted as such by other Deaf persons and uses Sign within the Deaf community.

deaf-mute:
Unacceptable. A deaf person may choose not to use his/her voice; this does not make him/her a “mute”.

deaf and dumb:
Offensive. NEVER use this term!!

Deaf-plus:
Although it has been used for many years to refer to people who have disabilities in addition to deafness, the preferred terms now are “Deaf with mental disabilities”, “Deaf-blind”, “Deaf with CP”, etc.

Sign language: (I took ASL 101 years ago, I can get by on Sign Language quite a bit)
The official language of the Deaf community. Should always be capitalized, just as “English” and “French” are capitalized, because all three are legitimate languages.

TTY:
The proper acronym for the special devices used by deaf, hard of hearing, and hearing people to communicate with each other through the telephone system. The French term is ATS.