Frequently Asked Questions FAQs Assistive Listening Devices

ALDs (Assistive Listening Devices) are amplification systems designed specifically to help people hear better in a variety of listening situations. ALDs can be used with a personal hearing aid or by themselves to help overcome background noises and distance from the sound source. The basic function of an ALD is to improve the "signal to noise ratio" for the listener. This means that desired sounds (signals) are amplified, and undesirable sounds (noise) are minimized.

ALDs can be used in many listening situations. They can be used to enhance sound in large public facilities or in group situations. They be used to improve your enjoyment of the TV, stereo or conversations.

Choosing an ALD is based on the listening situation and your listening needs. The types of ALDs include Personal Amplified Systems (A), Infrared Systems (IR), FM Systems (FM), Loop Systems (L) and Soundfields (S).

Personal Amplified Systems (A)

Personal amplified systems are designed to be very portable and can be used anywhere, indoors or outdoors. They are great for one-on-one conversations and TV listening. They are particularly helpful when in a car and it is difficult to face the person who is speaking. The units are pocket-sized and can be used with your choice of earphones, headphones, neckloops or telecoil couplers.

Infrared Systems (IR)

Infrared systems transmit sounds by invisible light beams. To be effective, the receiver must be within direct line of sight of the light beam from the transmitter. There is added security in an infrared system because sound cannot "spill over" to other rooms. (Many multiplex theater facilities are equipped with infrared systems for this reason). These systems cannot be used outside because of interference from sunlight. Bright, incandescent light may also cause interference.

Infrared systems are perfect for TV listening and small group meetings. Relatively easy to set-up, the transmitters connect directly to TV audio output jacks or can be used witha microphone. Receivers come in lavalier or headset styles.

FM Systems (FM)

FM systems transmit sound from the speaker's microphone to the listener's receiver via radio waves (frequency modulation), generally on 72-76MHz frequencies. The speaker wears a compact transmitter and a microphone, while the listener uses a portable receiver with headphone or earphone. Those with hearing aids equipped with a telecoil can use a telecoil coupler. They are ideal for classroom/meeting use and work well both indoors and outdoors. If multiple FM systems are used near each other, separate broadcast frequencies should be used as FM signals are not limited to line of sight and can penetrate walls and ceilings.

Loop Systems (L)

Based on a principal of electronics called electro-magnetics, these systems are easily used by those having hearing aids equipped with a telecoil circuit. The technology consists of a loop wire which is placed around a listening area. A special amplifier and microphone is used by the primary speaker. Speech signals are amplified and circulated through the loop wire. Those wearing telecoil-equipped hearing aids can pick up the resulting energy field and have it amplified by the telecoil. Those who don't have telecoil-equipped hearing aids can use special receivers with earphones to pick up the magnetic signal. Easy to install, they can be used in classrooms, places of worship, auditoriums, small meeting rooms and automobiles.

Soundfields (S)

Wherever a large PA system is impractical or where audio needs to be amplified for people to hear better, a soundfield may be the solution. Soundfields are not just beneficial to individuals who are hard of hearing - they can help in any situation where audio needs to be amplified for people to hear better, no matter if they wear hearing aids or not. Best known in the education industry, soundfields are also suitable for conference rooms, training centers, theaters, places of worship, courtrooms, convention centers and ballrooms, even cruise ships and tour buses.