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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, certain communication needs
may not be solved by simply using hearing aids.  Special devices have been developed to help meet challenges
involving telephone, radio, television, or the inability to hear
the door chime, telephone bell, and alarm clock. Like hearing
aids, assistive listening devices and alerting devices make
sounds louder. Typically, a hearing aid makes all sounds in the
environment louder. Assistive listening devices (ALDs) and
alerting devices can increase the loudness of a desired sound,
like a radio or television, a public speaker, or an alarm
system, or may make an auditory alarm (such as a smoke signal)
into a visual alarm (such as a strobe light). |
| While hearing aids may do well in the majority of environments, they are not perfect. A basic problem remains in which a personal hearing aid falls short. That problem relates to the physical distance between the microphone of the hearing aid and the source of the sound desired to be heard. It would be ideal to have the sound directed to the listener without losing any intensity. |
 Ways of achieving this effect is through infrared transmission, FM transmission or induction loop transmission. Systems using this technology are often found in many theaters, concert halls, houses of worship and households. One of the best uses is for television listening. The portable transmitter (usually smaller than most cable boxes) and microphone are located near the TV speaker. The sound picked up by the microphone is then transmitted at the same intensity to a receiver worn by the listener. These devices can transmit with minimal distortion over a considerable distance (up to 50 feet). |
 Assistive Listening Devices (ALDs) are becoming increasingly
common in public places, due to the legislative enactment of the
Americans with Disabilities Act. |