See Americans with Disabilities Act.

Alerting Device

Visual or tactile devices to alert a person who cannot hear door knocks, telephone rings, smoke/fire alarms, etc.

Americans with Disabilities Act (ADA)

The Americans with Disabilities Act of 1990 Public Law 101-336 prohibits discrimination on the basis of disability by public entities.

Amplified Phone

A phone equipped with volume control on the handset. Public coin-operated phones have a volume control button on the wall unit.


Automatic Speech Recognition

Assistive Listening Device (ALD)

Technical tool to assist people with hearing loss, with or without a hearing aid. It brings the speaker’s voice directly to the ear. Helps to overcome the problems of distant and surrounding noise.

Audio Loop (Induction Loop)

Uses electromagnetic waves for transmission of sound. The sound from an amplifier is fed into a wire loop surrounding the seating area (or worn on the listener’s neck) which broadcasts to a telecoil that serves as a receiver. Hearing aids without a T-switch to activate a telecoil can use a special induction receiver to pick up the sound.

Auxiliary Aids and Services

The Department of Justice regulation provides a comprehensive list of auxiliary aids and services required by the ADA to help overcome communication barriers. Examples of auxiliary aids and services are assistive listening devices, interpreters, notetakers, captioning, etc.

Captioned Telephone

The text of the conversation is displayed on a monitor built into the phone so the person with hearing loss can follow the call. A special phone is required.

CART – Communication Access Real-time Translation

CART or Communication Access Real-time Translation is the verbatim, near instantaneous conversion of spoken language into text. A stenotype machine, notebook computer, and real-time software is used to produce the text. The text is usually displayed either on a screen by a projector connected to the notebook computer, or on a notebook computer or computer monitor. CART is usually utilized by people with hearing loss who use spoken language as a primary mode of communication. However, some culturally Deaf people (whose primary mode of communication is sign language) can use CART as well.

Certified Hearing Dog

A dog that has completed extensive training to alert its owner to a variety of sounds in different environments. These dogs are usually identified by a bright orange leash with black lettering.

Closed Captions

Text display of spoken dialogue and sounds on TV and videos visible only to those using a caption decoder or TV with a built-in decoder chip.

Cochlear Implant (CI)

A cochlear implant is an electronic device that is surgically implanted and worked by directly stimulating functioning auditory nerve fibers in the inner ear. Cochlear implants convert sound waves to electrical impulses and transmit them to the inner ear, providing people with a severe to profound hearing loss the ability to hear sounds and potentially better understand speech without reading lips.

Communication Access

Accommodations that provide an environment where persons with hearing loss can communicate.

Compatible Telephone

Generates a magnetic field that can be picked up by turning on a “T-switch” to activate the telecoil in a hearing aid. The Hearing Aid Compatibility Act of 1988 mandates that all telephones manufactured in the United States from 1989 on should be hearing aid compatible.

Computer-Assisted Notetaking

Visual display of the speaker’s words. A notetaker types on a computer keyboard a summary of what is being said. The notes are displayed on a projection screen or monitor.

Cued Speech

A sound-based visual communication system which in English uses eight handshapes in four different locations (“cues”), in combination with the natural mouth movements of speech, to make all the sounds of spoken language look different.

Decibel (dB)

A unit used to express the intensity of a sound wave in logarithmic ratios to the base often. Sounds of different frequencies need to be from 0-20 dB in intensity to be heard by normal ears. If more than 20 dB is needed, then further hearing evaluation would be recommended.


Describes people who usually have no useful residual hearing and who generally use sign language as their primary mode of communication. This group of people are culturally Deaf and uses the uppercase “D” when writing the term. However, people who are audiologically deaf (using a lowercase “d”) generally use their residual hearing with speechreading, amplification, hearing aids and/or cochlear implants, and other hearing assistive technology. They may also learn sign language but are oral and don’t use it as a primary mode of communication. Based on the age at the time of loss of hearing, people who are deaf are categorized into two groups: congenitally deaf – those who were born deaf; and adventitiously deaf – those who were born with hearing but whose sense of hearing became non-functional later in life through illness, accident or age-related (presbycusis). The term deaf should always be used with a people descriptor; for example, people who are Deaf; people who are deaf; deaf people. The phrase “the deaf” should not be used. See Glossary for definitions of “hard of hearing” and “hearing loss.”

Effective Communication

A term used in the ADA as a standard for access for people with hearing loss. A public accommodation must provide an auxiliary aid or service where necessary to ensure effective communication with individuals with disabilities. The Department of Justice strongly encourages staff of public accommodations to consult with the individuals before providing them with particular auxiliary aids or services.


Federal Communications Commission

FM (Frequency Modulation)

A transmitter which broadcasts the signal by radio waves from the sound source to a receiver worn by the listener. Useful in large indoor or outdoor locations, since it can cover several hundred feet and pass through physical obstructions.

Hard of Hearing

Hard of hearing is a descriptive term used when making the distinction among people with hearing loss; for example, people who are deaf and hard of hearing. People often use the term hard of hearing to describe themselves no matter the audiological level of hearing loss. Typically, people who use residual hearing, amplification and/or hearing assistive technology and who do not use sign language as a primary mode of communication, consider themselves hard of hearing rather than deaf. Generally, people who consider themselves hard of hearing, no matter their level of hearing loss, are committed to participating in the hearing world using speech reading, residual hearing, technology, and sometimes sign language. The term hard of hearing is always used with the “people” descriptor as in “people who are hard of hearing” or “hard of hearing people.” The term “the hard of hearing” should not be used.

Head-End Decoding

Hotels with in-house television cable systems can provide closed captioning services by head-end decoding. The TV signal at the master antenna (head-end) is split, and one of the two signals is run through a closed caption decoder. The decoded signal is outputted to an unused TV channel of the in-house cable distribution system. Viewers can have a choice of the same program on a channel with captions or on another channel without captions.

Hearing Aid

An amplification device to assist persons with hearing loss. There are different kinds of hearing aids which are distinguished by how they are worn. They might be in-the-ear (ITE), in-the-canal (ITC), behind-the-ear (BTE), or on the body. The technology is still imperfect, and hearing aids do not correct hearing loss. Newest developments include programmable aids.

Hearing Dog

See Certified Hearing Dog.

Hearing Loop (Also see Audio Loop)

A wire that circles a room and is connected to the sound system. The loop transmits the sound electromagnetically. The electromagnetic signal is then picked up by the telecoil by flipping the t-switch in a hearing aid or cochlear implant.

Hearing Loss

Describes someone with any degree of hearing loss ranging from mild to profound. There are 36 million people with hearing loss in the United States. The term hearing loss can encompass both people who are deaf and people who are hard of hearing.  Most people with hearing loss use residual hearing and use hearing assistive technology such as hearing aids and/or cochlear implants. A small number who are culturally Deaf use sign language as a primary mode of communication. HLAA mostly uses the term people with hearing loss in descriptive writing and avoids using the term “hearing impaired.” Hearing-impaired is an audiological term, and HLAA avoids using it when referring to an individual’s hearing loss. See this Glossary for the definitions of “deaf” and “hard of hearing.”


Similar to FM except that it uses invisible light waves to transmit sound. Frequently used in theaters.

International Symbol of Accessibility for Hearing Loss

A symbol used to denote communication access. This symbol is an outline of an ear with a slash through it to identify that a room or venue is hearing-accessible. There is also another similar one with a “T” in the lower right-hand corner to identify the room or venue has a wireless hearing assistive technology known as a hearing loop installation connected to a sound system.

Interpreter-Sign language

Visible movements of hands, body, and face that replace the vocal elements of a spoken language. Depending on the communication situation and personal preferences, people who have hearing loss or who are deaf in the United States who use sign language might communicate using the unique grammar of American Sign Language (ASL) or some variety of signing that uses features taken from both ASL and English Sign Language.


A skill used by a person with hearing loss to try to understand speech by watching the lips. The term “speechreading” is now recognized as being more descriptive since it includes watching the facial expressions and body language, as well as the lips of the speaker.


A person who takes notes on a blackboard, overhead projector, notebook, etc. Keywords and phrases are written to enhance understanding for the person with a hearing loss.

Oral Interpreter

The interpreter silently mouths the words of the speaker so they are visible on the lips. Used when the person with hearing loss uses speechreading to understand the conversation.


An otologist/neurotologist is a board-certified otolaryngologist who provides medical and surgical care of patients, both adult and pediatric, with diseases that affect the ears, balance system, temporal bone, skull base, and related structures of the head and neck. The neurotologist is knowledgeable of the basic sciences of hearing, balance, nerve function, infectious disease and anatomy of head and neck. Their diagnostic, medical, and surgical skills include treatment of hearing loss and tinnitus, dizziness, infectious and inflammatory diseases of the ear, facial nerve disorders, congenital malformations of the ear, and tumors of the ear, hearing nerve, and skull base. As part of a team with neurosurgeons, they manage diseases and disorders of the cranial nerves and skull base.

Personal Sound Amplification Products

Known as “Personal Sound Amplification Devices,” or by the acronym PSAP, are defined by the U.S. Food and Drug Administration as wearable electronic products that are intended to amplify sounds for people who are not hearing impaired. They are not hearing aids, which the FDA describes as intended to compensate for impaired hearing. 


The term used to describe the slow, progressive type of hearing loss that goes along with aging. At age 65, one in every three persons has a hearing loss.

Proprietary hearing aids

Proprietary hearing aids (locked hearing aids) are hearing aids whose software is locked and can only be serviced by a limited number of providers.   If you don’t like your provider, finding someone else to service your hearing aids may be difficult.  Same applies if you move.

QuickSIN test measures a person’s ability to hear speech in noise. During the test, the patient uses both ears together (binaural hearing) to repeat sentences. Binaural hearing ability is essential for communication in noisy settings and for other aspects of functional hearing, such as sound localization and recognition of environmental sounds. In this test, the patient is required to repeat sentences with competing noise being presented from different directions.

Real Ear Measurement

Real Ear Measurement is a series of tests used for verification of hearing aid performance. The computer will show how a patient’s hearing loss can improve with a hearing aid by showing overall volume and areas of amplification with and without the hearing aid.

Real-Time Captioning

The process of producing either open or closed captions simultaneously with a live event. Real-time captioning incorporates a specialized computer system and stenographic keyboard much like those used in courtrooms.

Reverse Oral Interpreter (Visible-to-Spoken)

A professional support specialist who is trained to read the lips of a person with impaired speech, and then voice the message for the benefit of hearing persons. This type of interpreter can be used in a hospital to read the lips of patients who are able to move their lips but are not able to produce sound, due to a tracheostomy or a laryngectomy.

Sign Language

See Interpreter.

Signal-to-Noise Ratio

The relationship of a primary signal (a person talking) to the level of the ambient background noise. People with hearing loss need a much better signal-to-noise ratio than people with normal hearing.


See Lipreading.

T3 Smoke Detector Alarm Pattern

T3 is a temporal pattern that consists of 3 beeps and then a pause, then 3 beeps and then a pause….etc. T3 is used for smoke detectors exclusively.

Telecoil / T-Coil

A telecoil is a small copper coil that is an option on most hearing aids and is built into cochlear implant processors.   They are used with a hearing aid compatible telephone, assistive listening device, and audio loop system. They are also known as t-coils and were originally used to boost the magnetic signals from the telephone handset. The telecoil is activated by a t-switch on the hearing aid or cochlear implant. All landlines and some cell phones are designed by law to be used with a telecoil.

Telecommunications Relay Service

Sometimes called dual-party telephone relay service. Enables text telephone users to communicate with a non-text telephone user by way of a relay service communications assistant. The ADA mandated this nationwide relay service by 1993.


A setting on a hearing aid that can be used with a hearing aid compatible telephone, assistive listening device, and audio loop system. When the hearing aid is switched to “T”, it activates the induction telecoil (the technical name for the “T” switch), causing the hearing aid to pick up the magnetic field generated by the “hearing aid-compatible” telephone assistive device, or audio loop system being used.

Text Telephone (TT)

Formerly TDD or TTY – a text telephone is a telecommunications device used by those who cannot understand on the phone. A typewriter-like unit shows the conversation on a screen so that it can be read. The transmission is with a special coding called Baudot or ASCII.


Telecommunications Device for the Deaf. See Text Telephone (TT).


See Text Telephone.


Tympanometry is an examination used to test the condition of the middle ear and mobility of the eardrum and the conduction bones by creating variations of air pressure in the ear canal.

Videotext Display

A real-time speech-to-text system. The words of the speaker are typed on a keyboard similar to that used by court reporters. The text is then projected onto a screen that can be read by the audience. Specially trained personnel operate this system.

Visual Alarm Signal

A visual signal (flashing light) giving notice that an audible event has taken place. For example, doorbell, fire alarm, ringing telephone. Some systems monitor a single event; others can monitor several events and indicate which event has occurred.

Volume Control Telephone

See Amplified Phone.