2000 Conference Proceedings

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An Overview of Hearing Assistance Technology

David Baquis
Director, SHHH National Center on Assistive Technology

Although people with hearing loss comprise the largest disability group, their needs are poorly understood and often go unaddressed. This lack of awareness is prevalent both inside and outside of the disability community. Those who attempt to meet the needs of people with hearing loss need to consider the diverse needs of individuals, who experience hearing losses ranging from mild to severe and who use a variety of technologies to help them cope.

This is not an insignificant group. There are an estimated 28 million people with hearing loss in America, which is 10% of the population. The number of people with hearing loss is predicted to rise significantly as the aging baby boomer generation enters middle age – the time when hearing loss incidence increases.

Although hearing loss affects one in three older people, it is a concern to younger people as well, especially working-age hard of hearing adults who are unemployed. Many of those adults can be helped with a combination of advocacy, technology and communication strategies.

There are many ways of coping with hearing loss. Assistive technology is just one strategy. Other resources include: using hearing aids, when recommended; participating in hearing loss support groups; and reading educational publications with information on subjects such as stress control and personal advocacy.

A needs assessment is an important precursor to learning about hearing assistance technology. The assessment anticipates different situations where hearing can be challenging and uses questions to help determine an individual’s areas of difficulty. It is important to begin with various questions about someone’s challenges to prevent overlooking problems that consumers forget to ask about. For example, they may inquire about a telephone amplifier to better understand conversations. When this problem is presented, it also becomes useful to know if they miss phone calls and need a telephone ring signaler.


Assistive technologies help people with hearing loss acquire greater confidence in their communication skills, expand their abilities to maintain independent lifestyles and reach their full potential scholastically, professionally and socially. An important challenge to overcome, however, is lack of awareness about what devices and services are available.

Assistive technology is a broad term that encompasses both devices, such as TTYs, as well as related support, such as relay services. Other services include: equipment distribution programs; assistive device demonstration centers; financial aid programs and legal advocacy services.

Some devices, such as flashing wake-up alarms, were specifically designed to help someone with hearing loss. Other devices, such as personal computers, were originally developed for general purposes, but nevertheless afford important secondary benefits to people with hearing loss. Hearing assistance technologies can be grouped into three categories: listening devices, telecommunications, and alerting devices.


An assistive listening system (ALS) is designed to amplify and clarify sound by reducing the effect of distance between the user and the sound source. Such systems can also help minimize background noise and can help compensate for poor acoustics. There are three types of ALS technologies: inductive loop, infrared and FM. Loops transmit an electromagnetic field, infrared systems emit light waves, and FM systems send radio waves. Each works well, operates without wires, and can be used with or without hearing aids. An array of receiver attachments is available to meet varying individual needs and listening preferences.

People who use a hearing aid equipped with a telecoil may prefer an inductive loop, since they will not need additional receivers; instead, users simply switch their hearing aid to the T position. Infrared systems offer the advantage of privacy. Such systems might be a good choice for courtroom situations because the light waves they transmit don’t pass through walls. FM systems are portable, making them a popular choice for classroom situations, since both the teacher and student can use battery-operated components, and the student can move around without interfering with reception.

All three systems are susceptible to interference. Loop systems are occasionally affected by electromagnetic fields, but some sources, such as computer monitors, can be turned off at times. Sunlight or certain fluorescent lights can affect infrared systems, but a more powerful emitter and a newer model receiver may help compensate for that. Pagers and other radio transmitting devices may affect FM systems, but changing FM frequencies may help.

One key to successful use of any ALS in a meeting situation is effective placement of microphones. For example, during a large meeting, one microphone might be used by a primary speaker, with audience members asked to use side microphones. A cordless FM microphone could also be passed around as needed. For a medium size meeting, the tables could be equipped with a single microphone for every two or three people. Conference microphones, which pick-up the speech of several people in the vicinity, are also available.

For a small meeting (three to four people) a personal listening device may be effective. It involves connecting both a microphone and listening attachment to the same device, an amplifier. This offers two advantages: it is relatively inexpensive (approximately $200) and portable (the size of a deck of cards). Such a device is often used for one-to-one conversations, such as when driving a car or when speaking to a doctor. This is not wireless, so could not transmit across a distance, although in some cases it can be used with several microphones.


People with hearing losses can get information by phone in one of two ways: amplification or text. There are four types of amplifiers: portable, in-line, handset and phone set. Portable amplifiers strap onto the telephone handset. They are convenient for travel but are not usually practical for regular use.

In-line and handset amplifiers are the most popular choices because they are relatively inexpensive and generally equal in effectiveness. Most amplifiers designed for hard of hearing people offer a 20dB gain, although devices with gains up to 40dB are also available. Some amplification phones offer a differential boost in volume, resulting in a reduction of "muddling" sounds for some users because the low frequencies are not amplified as much as the high ones. Telephone products, such as these, are sometimes available free of charge through equipment distribution programs.

Electronic incompatibility can be a problem: Some amplification handsets do not work on certain phones as evidenced by a buzzing sound or the inability of one party to hear the other. The problem sometimes occurs at hotels, which loan amplifiers to customers, to use with their room phones. The cause is related to the type of handset microphone and circuitry being used. The solution may involve obtaining a universal amplifier, which is designed to work with most types of phones.

TTYs allow users to read the text of their phone conversations. One option is for both parties to use a TTY. However, this text telecommunications approach can be used, even when the hearing party doesn’t have a TTY. In this case, a telecommunications relay service will use a communication assistant to bridge the gap by typing the hearing party’s conversation into the TTY. Instead of typing, a hard of hearing person with good speech can use a relay service option called "voice carry over" to respond orally. Some TTYs specifically designed for voice carry-over do not include a keyboard.

Cellular phones offer users both convenience, and security. Accessible cellular phones will be hearing aid compatible; provide amplification and feature an audio jack, allowing connection to attachments for listening through both ears. Hard of hearing consumers also desire a vibrating ringer, available on select models. Digital wireless phones have generally not been shown to work reliably with hearing aids or TTYs at this time, although the industry is working towards a solution for both.

Other telecommunication devices, which provide parity for hard of hearing people, include: fax machines, pagers and integrated wireless products (which may combine fax, pager, TTY and e-mail). Most pagers can vibrate and some display the text of messages. The Internet is especially a boon to hard of hearing people because it can be used for instant messaging, conference calling and e-mail.

New developments in text telecommunications include videophones, text based office intercom systems and TTY accessible interactive voice response systems.

Some of the optional services offered by local phone companies hold advantages for people with hearing loss. Caller identification, for example, allows consumers to see the number of a caller on a TV or display box and to return that call through a relay service. Distinctive ringing allows households with both hearing and hard of hearing members to dedicate one number for TTY use and the other for voice calls. Voice mail service allows consumers to listen to messages using amplification devices. These custom calling features require an additional monthly fee.


Like the telephone, there are two ways to know what is said on TV: reading captions or listening through amplification. With regard to captioning, all TVs, 13 inches or greater, sold and manufactured in the U.S. must have closed caption capability. Older TVs can be modified through the use of a telecaption decoder. The Telecommunications Act of 1996 requires captioning for many of the TV programs and videos being produced.

With regard to amplification, it is also possible to connect inexpensive assistive listening systems to the TV. These allow consumers to hear sounds more clearly without interfering with the enjoyment of other listeners. ALSs can also be used with stereo systems.


Smoke alarms, a telephone ringing, doorbells, a baby crying, wake-up alarms and security systems are some of the sounds that can be transmitted to a person with hearing loss through an alerting device. The most commonly used systems employ loud ringers, flashing lights or portable vibrators and can range from relatively simple to very sophisticated. A simple, inexpensive telephone light flasher will only be visible at the site where it is installed. A more comprehensive system could signal a consumer to a variety of events through use of transmitters placed at various points in the house.

Another signaling device, a personal pager is only about $80. It allows a user to alert someone in the vicinity (via tone or vibration) and does not require a monthly fee, as do telecommunications pagers.

Two types of alerting devices are available to help hard of hearing drivers. One is an emergency siren indicator that flashes a panel of small lights on the dashboard to signal the approach of an ambulance, fire engine, or police car. The other is a turn signal reminder that flashes a light or makes a progressively louder sound if the driver forgets to turn the signal switch off. In the United States, four car manufacturers have offered to reimburse users for the cost of buying and installing one or both of these devices.


Advocacy is an important component with regard to the effective use of assistive technology. Consumers must understand governing public policies and exercise their rights to acquire and use assistive technology. For example, in the United States, the Americans with Disabilities Act (ADA), mandates that reasonable accommodations be made available to persons with a hearing loss in the workplace, local and state government agencies and public arenas. It is important for consumers to make use of resources already in place since this is one of the best way to support advocacy efforts to improve public accommodations.

Unfortunately, hard of hearing consumers often miss out because they feel uncomfortable asking for assistance. It is often in commonplace situations, such as Thanksgiving meals, weddings, funerals and graduation ceremonies, that hearing access is most valued. Membership in consumer groups, such as SHHH, helps consumers learn assertiveness skills and become comfortable using assistive listening devices.

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