Induction Hearing Aid Loops (T Loops)


Audio induction loops, also known as T loops is an established technology that helps the hearing impaired to increase the clarity of amplified sound in any busy environment and work in conjunction with the user (hearing impaired person) of a hearing aid.


Frequently Asked Questions

Where can Induction Loops be used?

Induction Loops can be beneficial in a very wide range of environments, from large venues such as theatres and conference facilities, to one-to-one communications such as ticket counters and meeting rooms. They are the only effective solution to assist hearing aid users in transport environments, in vehicles, terminals and stations.

Examples of existing applications for induction loop systems:

Transport Systems 
Airports, stations and transport networks, Elevators, Help points, Car park access points

Taxis and private cars, Minibuses, Coaches, Trains, Trams and Boats

Theatres, cinemas and concert halls, Stadia and sports venues, Places of Worship, Conference and lecture halls

Counters, Intercoms and entry-phones, Drive-throughs, Help points

Meeting rooms, Video conference facilities, Desks and offices

TV rooms, Phones, Individual car systems

Lecture halls, Classrooms

Public address systems, Voice alarm systems, Help points

Induction loop systems are not suitable if:
– There is substantial background noise, which will reduce the effectiveness of any assistive listening system
– There is no practical way to install the loop cable (sometimes requires creative solutions – ask if you are not sure!)
– There is no sufficiently good quality audio source available

How do Induction Loops Work?

An induction loop system transmits an audio signal directly into a hearing aid via a magnetic field, greatly reducing background noise, competing sounds, reverberation and other acoustic distortions that reduce clarity of sound.

This diagram illustrates how they work.

hearing_loop_diagram Amertronic photo


Audio Inputs 1, either from an existing audio source such as a P.A. system or from dedicated microphone inputs feed an audio signal into an Induction Loop Amplifier 2. The amplifier drives a current into a Loop 3 or series of loops. As the current flows through the cable it creates a Magnetic Field 4 in the required area – careful loop and amplifier design ensures that the vertical component of the field is even and free of dropouts and dead zones wherever the user might be. Inside most Hearing Aids 5, a small coil known as a Telecoil 6 picks up the magnetic field signal, which is amplified into a high quality audio signal delivered directly to the ear of the hearing aid user.

How do Induction Loops help?

People who suffer from hearing loss – the unseen disability – require more than just increasing the volume of sound into their ears.

The loss of hearing is generally associated with the neurological processing of information in the brain. People with normal hearing require a signal to noise ratio of 6dB for a reasonable level of intelligibility. This represents quite a noisy background, which might be reverberation, air conditioning, ventilation systems or background noise such as a crowd of people.

When a person loses about 80% of their hearing, they generally need a signal to noise ratio of 15 to 20dB. This can be difficult to achieve unless the wanted signal is taken straight from the basic source and transmitted directly through the loop system, avoiding any reverberation or additional ambient noise.

Transient situations, such as ticket counters, information and help points, etc., are the worst areas for listening, though even in churches, theatres and lecture / conference rooms, there is often sufficient degradation of the signal to seriously affect intelligibility. In most situations it is impractical to issue any form of separate receiver and the use of the individual’s hearing aid is a major step to bringing people with hearing loss back into full contact with their environment. Only induction loop systems are capable of doing this.