Assistive Listening Devices
Assistive Listening Devices (ALDs)
Beyond hearing aids, we also have several types of ALDs to improve hearing for people with hearing impairments. An ALD works with audio devices including TVs, public-address systems such as those found in churches, and phones. ALDs can improve your hearing in a variety of situations where hearing aids may fall short, by offering selective amplification and better sound-to-noise ratio (SNR).
What kinds of ALDs are available?
Several kinds of assistive listening devices are available. Some types are designed for facilities like classrooms, places of worship, theaters, airports and similar locations. Other kinds are for single-person use or one-on-one conversations in small locations. All ALDs can be utilized with or without hearing aids and cochlear implants.
ALDs designed for large facilities include systems such as Hearing Loops, Infrared (IR) and Frequency-Modulated (FM) equipment.
Learn more about Hearing Loops [Link to Hearing Loops content]
A telecoil, or “t-coil,” is a tiny coil or wire used in many cochlear implants and hearing aids to act as a small wireless receiver. It’s designed to help clarify sounds for people when using the telephone.
T-coils are also used with many ALDs, such as FM, IR and Hearing Loop systems. The telecoil can reduce or eliminate background noise and customize desirable sounds for each individual user’s needs.
Assistive listening devices often use FM radio signals in order to transmit the amplified sounds. They’re frequently used in classrooms, where the teacher uses a small microphone connected to the transmitter, while students wear receivers that are tuned to a special radio channel. FM signals can travel up to 300 feet.
Still, because radio signals can penetrate walls, multiple listeners in different rooms may need to use different channels to avoid cross-talk. Single-user FM systems are used to help people with hearing impairments hear one-on-one conversations.
IR systems rely on infrared light to carry sounds. The transmitter converts sounds into IR signals and sends them to a receiver worn by the listener. The receiver converts the IR signal back into sound. Unlike FM and some other technologies, IR cannot penetrate walls, so it’s ideal for courtrooms and other confidential locations, or for schools and other places where competing radio signals might cause confusion.
Personal amplifiers are about the size of a cellular telephone. They work well in places where the above-listed systems are unavailable, or when the listener is traveling, watching television, or located outdoors. These devices amplify desirable sounds and reduce background noise. Some of them feature directional microphones that can be aimed toward the speaker or other source of sound.
What kinds of devices can help user communicate by telephone?
In the past, people with hearing impairments used text-enabled telephone equipment known as TTY or TDD devices, in order to communicate by phone. The same type of device, which uses a typewriter keyboard and a visual display or print-out, also helps people who have speech difficulties.
Nowadays, technologies have improved. Advances include voice-recognition software and captioned telephones that allow users to talk while reading a displayed real-time transcript of the conversation.
Alerting or alarm devices use light, sound, vibration or a combination thereof to warn users when a particular event is happening. Devices such as clocks and wake-up alarms offer plenty of options to people who have difficulty in hearing the sounds given off by standard alarm devices.
Visual alert signalers use flashing lights or vibrations to warn users when doorbells and phones are ringing. And, remote receivers and portable vibrating pagers can extend the effect range of such alerts.
Current research regarding assistive listening technologies
Researchers continue to make rapid progress in developing better ALDs. Among other technologies, researchers are testing portable devices through which groups of users can enjoy amplified and enhanced speech while conversing in noisy environments.
If you’d like to hear more, and hear more clearly, we can help
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