Induction loops are a type of assistive listening technology. They have been around for many decades. Every so often a news article generates a burst of interest in loops. The following is an explanation of loops; what they are, what they do.

A loop is a cable which is installed around the perimeter of a designated listening area. The cable is linked to an amplified sound system. The amplifier receives a signal from an audio source (speaker’s microphone, stage mics, TV, movie soundtrack) and sends it around the room, through the cable, in the form of magnetic energy. This signal can be picked up by any magnetic receiver located within the loop. For the purposes of hearing aid users, this receiver is usually a telephone coil (t-coil) located inside the hearing aid itself, though it can also be picked up by non-hearing aid users through dedicated receivers linked to headphones or ear-buds.

When the t-coil is activated, the signal from the loop is transmitted directly to the hearing aid. For the listener, this can be preferable to simply receiving the signal “through the air” via loudspeakers for several reasons.

1. It improves the “signal-to-noise ratio”. Simply put, the signal coming through the loop stands out from the ambient sounds of the room because it is a direct transmission from the sound source.
2. It reduces the impact of factors which can degrade a sound signal, such as reverberation of the sound from the loudspeakers in the room.
3. It allows for processing of the signal through the circuitry of the hearing aid, which is programmed to accommodate the specific hearing loss of the listener.

For these reasons, the presence of a loop system can be very convenient and effective for hearing aid wearers who have t-coils. Hearing aids without t-coils cannot pick up the loop directly, though some contemporary “streamers” and other current hearing aid accessories can pick up the loop and send the signal to the hearing aids.

It is important to remember that, for the most part, the usefulness of loops is limited to designated, “looped” listening environments. I mention this because patients often ask if this technology can help them in restaurants and parties, or other challenging environments. The answer to that question is usually…no. That is not what loops are designed for.

The loop has a pretty easy job….there is a dedicated sound source and a designated listening environment. It is not a mobile solution. A restaurant or party is a much more varied and complex environment, where people move around, change position, and where there are always many sound sources that need to be heard, as opposed to one simple source being transmitted through a loop.

It follows then, that loops are not the answer for all listening situations. However, when present, they are always welcome and very useful. If a meeting room or entertainment venue has a loop, there is usually a posted sign indicating that the room has been looped for t-coil use. Sometimes this information is available on websites or within promotional materials for particular theatres or auditoriums.

Although the technology has been available for many years, it is still not very common to find looped environments in the United States. However, due to the efforts of various advocates, suppliers, and demand stimulated by articles, there has been some progress with loops and they are more common here than in the past. Loops are more common in European countries where they have typically found wider acceptance.