Assistive listening devices are systems that help people with hearing loss hear teachers, performers, television shows and other sounds more effectively. Assistive listening devices, or ALDs, use wireless and wired technology and both sound and light waves, according to the RIT National Technical Institute for the Deaf. ALD can help a person with hearing impairments function in the hearing world when it comes to going to school, attending a work-related conference or enjoying a television show with family.
Induction Loop Systems
The American Speech Language Hearing Association (ASLHA) says the induction loop system is a common assistive listening device that users can buy on an individual basis and use where and when appropriate. The induction loop system uses an electromagnetic field to conduct sound from a microphone, used by the speaker, to the listener's hearing aid. Adjustments for volume are made by the listener by adjusting his hearing aid without disturbing other people in the room.
Sound Amplification Systems
Sound amplification systems make a person's voice louder and can be an effective tool in a large auditorium that has a poor acoustic quality. The instructor or presenter uses a microphone as she talks, and a speaker is placed near the person who will benefit from the sound amplification system.
Sound amplification systems can be used on a smaller scale as well. Telephones can be fitted with amplifiers to make telephone conversations more comfortable and productive for a person with hearing loss.
FM Systems
Assistive listening devices called frequency modulation, or FM systems, operate through radio waves. FM systems are small and portable when compared to larger ALDs such as an induction loop or sound amplification system. The person who needs sound amplification wears a receiver that picks up sound through his hearing aid. A microphone transmitter is used by the other person involved in the conversation, such as a dinner partner or a teacher in a classroom. Similar to a radio station, the strength of the frequency of this kind of ALD varies but may extend to up to 200 feet in some cases.
