Assistive Listening Devices
Cynthia Compton-Conley, Ph.D. - Gallaudet University, Washington, DC
Due to technological advancements in recent years, today's hearing aids do an excellent job of helping people meet many of their communication needs. However, sometimes there are situations where additional technologies may be needed. For example, some hearing aid users may continue to experience difficulty understanding speech in noisy environments, from a distance, as when watching TV or attending a movie or play, or while listening on the telephone. At bedtime, a person with even a mild to moderate hearing loss may not hear the smoke alarm located down the hall. This same person might miss a doorbell chime while listening to the TV a room away. Further, a child with normal hearing, who suffers from recurrent middle ear infections or who has a central auditory processing disorder, is at a definite educational disadvantage when seated in a typical classroom with poor room acoustics and excessive noise.
How Assistive Technology Can Help
Many auditory and non-auditory devices — collectively known as Assistive Technology, Assistive Listening Devices (ALDs), or Hearing Assistance Technology (HAT) — are available to help people with all degrees of hearing loss. These devices can help facilitate improved face-to-face communication, reception of electronic media, telephone reception, and reception of important warning sounds and situations.
Devices to Facilitate Face-to-Face Communication and the Reception of Electronic Media
Auditory assistive listening devices can be thought of (roughly) as "binoculars for the ears." By placing a remote microphone next to the talker (or loudspeaker) or by connecting directly into the sound source (TV, VCR, MP3 player, etc.), these devices bring the desired sound closer to one's ear(s) before it has a chance of being mixed with noise and reverberation. The "captured" sound is then sent to the listener via a "hardwired" or "wireless" link. Three wireless systems can be used: FM (see below), infrared or inductive (audio loop). In order to use these systems, the hearing aid must be equipped with either a "telecoil" or a feature called "direct audio input (DAI)." DAI allows very tiny FM receivers to be plugged into the bottom of the hearing aid. DAI or a telecoil also allow body worn FM and infrared receivers to be used with more styles of hearing aids. Finally, a telecoil allows the hearing aid itself to function as the receiver when listening to a room-sized inductor (room loop) installed in a building (e.g. church, movie house). For greatest listening flexibility ask for hearing aids with telecoils built into them. And, if you want to have the opportunity to use the latest tiny FM receivers, think about purchasing behind-the-ear (BTE) hearing aids equipped with DAI.
Two types of visual systems are available to help people understand speech at a meeting or other live event: Computer-Assisted Note taking (CAN) and Communication Access Real Time Translation (CART), also known as Real Time Captioning.
Devices to Facilitate Telephone Reception
Special telephone amplifiers are available that replace the telephone handset, attach to the phone between the handset and the phone (in-line amplifiers) or attach to the handset and are powered by a battery (portable amplifiers). Each of these amplifiers can be used with or without a hearing aid. These standard telephone amplifiers can be coupled to a hearing aid either acoustically or inductively. With acoustic coupling, the amplifier is held up to the hearing aid's microphone. While this tends to work well with a CIC hearing aid, it may result in an annoying whistling sound (feedback) with the larger hearing aid models. However, if the larger models are equipped with a telecoil, then the hearing aid can be set to "T" and held next to the amplifier, with no feedback.
Special telephones with built-in amplification are also available in both standard and wireless handset models. Also available are devices that enable you to use your hearing aid(s) with a digital cell phone for distortion-and noise-free reception. For those who cannot understand over the voice telephone, even with amplification, there are other options such as the Voice Carry Over (VCO) or "read and talk" telephone. Used with the telephone relay service, VCO allows you to talk directly to the other party while an operator translates what the other party says to you into print that is displayed on a small LCD screen
Alerting devices allow hard of hearing and deaf people to be aware of many environmental sounds and situations in the home, in school or in the workplace, as well as for travel and recreation. Such systems use either microphones or electrical connections to pick up the desired signal and hardwired or wireless transmission to send the signal to you in a form to which you can respond. For example, when someone presses the doorbell button, when the phone rings or the fire alarm is activated, these events can trigger a flashing incandescent or fluorescent light, a loud horn, a vibrational device (pager, bed shaker), or a fan.
WHICH SYSTEM IS BEST?
A broad assortment of auditory and non-auditory technology is available to assist in removing the communication barriers of everyday life. Your hearing healthcare professional should be able to help you select the best system, or combination of systems, based on your own unique communication needs and lifestyle.