Assistive Technologies for Individuals Who are Deaf or Hard of Hearing

There are many devices and systems available to assist individuals who are deaf or hard of hearing in accessing the environment. Some devices convey information visually, and some devices enhance auditory information. These devices may be used by individuals of all ages and in a variety of environments, including home, work, school, social gatherings, meeting, hospitals, churches, and theaters.

Devices to Enhance Listening

There are a variety of Hearing Assistive Technologies, referred to as HATS, designed to overcome distance, background noise, and reverberation. Some of the assistive listening devices most commonly used are Frequency Modulation systems, called FM systems, Infrared systems, Audio Induction Loop systems, and other accessories to couple hearing aids to media such as phones, music players, computers, and tablet devices.   

FM systems: With FM systems, sound is transmitted directly from a microphone worn by a teacher or another person speaking, and transmitted via FM radio signals directly to an individual at a constant volume, regardless of the a person's distance from the FM microphone. There are two kinds of FM systems: personal and sound field. A personal FM system is coupled directly to a hearing aid or cochlear implant, with sound transmitted directly to the individual. A personal FM system needs to be set for each person using it. A sound field FM system provides increased and directed sound levels to a group of individuals. Special speaker units are placed strategically throughout a classroom or open space (e.g. auditorium, cafeteria, etc.) to direct amplified sound to the vicinity where needed. As a result, all individuals sitting within range of the speaker unit benefit from the amplified voice. Evidence is showing that even individuals who are not deaf or hard of hearing can reap the benefit of improved listening through sound field FM systems.  

Infrared and Audio Induction Loop systems: While not as common as FM systems, these assistive technologies may also be used for listening in large spaces, including schools, religious institutions, and theaters. An Infrared system uses invisible light beams to carry sound to a personal receiver. Different types of attachments may be connected directly to a personal hearing aid or cochlear implant, or sound can be transmitted to headphones or speakers. An Audio Induction Loop system is a cable (induction loop) that circles a room or is worn around the neck and transmits sound electromagnetically. The electromagnetic signal is picked up by the telecoil in a hearing aid, cochlear implant, or headset. To be tied into the audio loop, the telecoil is switched on in an individual's hearing aid or cochlear implant.      

Coupling accessories (for connectivity to media devices such as computers, TVs, tablets, smartphones, etc.): There are many accessories for hearing aids or cochlear implants that can connect to media devices. There are cables that plug directly from a hearing aid or cochlear implant into tablet devices or phones, or couplers which transmit sound wirelessly from hearing aids to media devices.

For more information about Hearing Assistive Technologies, see:
Hearing Assistive Technology (ASHA)
Video Series: Hearing Assistive Technologies (Hearing Loss Association of America)

Devices to Convey Information Visually   

There are a variety of assistive visual technologies including visual alerting devices, technologies to convert spoken language to text, and technologies to support telecommunication.  

Visual Alerting Devices  

There are devices available to help individuals alert to sound using visual support. Specially designed alarm clocks, smoke detectors, doorbells, timers, baby monitors, and phone alerting equipment are available to provide typically audible information in visual or vibratory ways. Some are designed with built-in lights or vibrators, and others adapt or connect to existing equipment. As with any other technologies, alerting and communication devices for individuals who are deaf come in a variety of styles and models, from a variety of companies, with a variety of prices.  


Captioning is an important vehicle to assist individuals who are deaf and hard of hearing with access to the media. TVs include settings for the user to enable closed captioning of programs that offer this feature. Closed captioning is also offered on many media devices. Logos with "cc" provided in TV guides or directly within the media program (i.e. YouTube) indicate when something is closed captioned. There are also theaters that offer open captioning for specific dates/times of movies.

For more information about captioning, see:  
Described and Captioned Media Program
Making Sounds Visible: National Association for the Deaf (NAD)
National Captioning Institute

Real-Time Transcription   

There are real-time transcription systems that provide instant translation of the spoken word into English text using a stenotype machine, notebook computer, and real-time software. The stenography may occur onsite or remotely. One commonly used system is Communication Access Real-time Translation (CART) that translates speech to text, word for word. Two other systems are C-Print and Typewell. These systems capture the essence of a discussion, rather than word for word. Regardless of which system is used, the captions are viewed on a screen or individual monitor and the process is quick with virtually no delay from speech to text.  

For more information see:
NAD Captioning for Access


Individuals who are deaf or hard of hearing have increasing access to communication via text or video through current technologies. Whereas TTYs (special teletypewriting devices designed to provide text communication via landline phones) were once the standard of technology to visually access phone communication, telecommunication opportunities which have been revolutionized for the general public (e.g. texting, video chat applications for computers, smartphones, and tablets), are now equally available to enhance communication access for individuals who are deaf or hard of hearing. TTYs are now rarely used.  

Another option is a captioned telephone. Similar to the captions displayed on TV, captioned telephones show word-for-word text of everything a caller says. Whether on a mobile phone or on a traditional household telephone, individuals can rely on the captions to help catch every word over the phone.

For more information about how this works, see: 
Listening and Spoken Language: Captioned Telephones

When both parties do not have a text communication system, all telephone companies by law provide a relay service to facilitate phone communication. Toll-free numbers provide access to a confidential operator trained in placing calls between individuals. In addition to a traditional relay service, where the operator reads a message that has been typed to them via a TTY, there are video relay services where the operator is a certified ASL interpreter. The deaf user signs to the interpreter, who then contacts the hearing user via a standard phone line, and relays the conversation between the two parties.

For more information, see:
FCC: Telecommunications Relay Service 

Developed at the Clerc Center, October 2014

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