Here are some common questions about Opus Technologies and its solutions.

Hearing loop amplifiers


A study revealed that more than 60% of the induction loop installation malfunction or don’t function and are away from the IEC-60118-4 standard demands. Indeed, the biggest difficulty lies in the implementation of the loop progression. This observation led us to brainstorm and to bring effective solutions in order to respect this standard.

What’s the point ?

An auditive loop or induction loop is a help system for the hearing impaired using a magnetic induction loop. With this system, sound from a microphone, audio system, TV or other equipment is transmitted wirelessly directly to the hearing aid to the person via a magnetic field generated by a specific amplifier. . This technique will eliminate ambient noise. This system is mainly used in public places (conference rooms, theaters, courts, churches, counters, etc.) but can also be installed at home. A large part of conventional hearing aids includes a “T” loop function.

How does this work ?

Generally, an auditive prothesis includes two positions, « M » and « T ». « M » position enables to perceive sound thanks to sound pressure with a built in a microphone, while « T » position receive directly audio signals transmitted by induction through a coil integrated to the hearing-aid. Some prothesis combine two operating modes, « MT » position. It enables hearing-impaired people to perceive simultaneously ambient sounds and signals transmitted by induction.

Working principles

An induction loop is generally installed in premises. The installation consists of an electric wire which browses premises perimeter forming a loop. The wire is linked to an audio amplifier. The hearing-aid includes a coil called « T » or « T-coil ». This coil, placed inside the prothesis, is also made up of a wire which do a lot of turns. The magnetic field generated by the big loop around the room will cross little loop in the prothesis and, thanks to induction principle, the electric signal in the big loop will go in the small ones. This way, we transmit the audio amplifier signal to the prothesis, which will restore it to the hearing-impaired person’s ear.
In a theater, for example, we will transmit, the movie’s sound. In a conference room, we will transmit the microphone’s sound. Etc..
The loop can be installed on the ground level or on the ceilling, specifically between 1,20m and 2,20m from the listening height. The loop is integrated in the building, along with the electric installation.
The fact that there is an auditive loop is often flagged by a blue logo which representing a crossed ear and a « T » letter.

Your project becomes ours …

An induction loop installation assembly impose the awareness of several factors, such as :
magnetic contamination
presence of metallic framework : ceillings, reinforced concrete, floor, metallic beams … etc.
The room’s shape : rectangular, square, distorded or sloping.
If several rooms have to be equipped in sequence. (Classrooms, offices)
The place’s configuration : theaters, amphitheaters, conference rooms, reception desks … etc.
The ideal heigh of the loop
Implementation possibilities.

It’s important to take all this elements into account as soon as possible in your project. It will enable you to do your installation under the best possible conditions.
Contact us, we will be able to guide you.

What you have to know.

When an induction loop installation is running, its magnetic field radiates outside the room you have to cover.

Generally, a peripheric loop overflow is equal to the loop’s width in every directions, so that a 10m x 6m loop will produce a 22m x 18m area.

Thoses radiations are perceived by fitted with hearing-aid people who are in adjacent rooms. To compensate this, we install an low-crosstalk induction loop system.

Low-crosstalk systems ensure your effectiveness.

A lot of situations exists, where the loop coverage has to be placed in a specific area, whether it is for security, or because of side by side rooms. Low-emergence systems reduce external radiations. These installation entail the implatation of two induction loops with a 90° phase offsetting in order to have consistent distribution without shadow area within the loop.

UHF Wireless System

Working principles.

A radio link settle in thanks to a (movable or fixed) transmitter and, at least, a dedicated receiver. The emitter receive an electric signal (audio source) which is converted into an electromagnetic signal, which is led to the antenna. The antenna emit the signal where it can be caught by one or several other antennas. This constitutes a fundamental difference with wired link for which a signal can only be received by the one which is on the other side of the wire. The signal is disseminated everywhere and can be received by any person with hearing device (headset or necklace loop). The receiving antenna lead the signal to the receiver from where is extracted the same electric signal as the one which was in the emitter’s input.

For hearing-impaired people with hearing devices, the magnetic loop necklace connected to the receiver enables to reproduce a magnetic field on a person scale, to transmit the signal to the hearing device.

Benefits of a UHF radio system.

The radio transmission system is an old technologie discovered at the end of the XIXth century by Heinrich Hertz and setted up by Guglielmo Marconi a few times later. It is a reliable and mastered communication method providing a long range compared to other wireless transmission systems.

The implementation  of a radio transmission system in a building is pretty simple and doesn’t need heavy work.

However, it is important to notice that, despite its long range, the radio wave can meet obstacles which are going to harm to the the spread between transmitter and receiver. These obstacles can be buildings, forests … Some obstacles, such as metallic walls, are absolute obstacles to electromagnetics wave transit. A speaker can leave the room equipped with the emitter and receive the signal on his receiver.

The radio transmission provides several application possibilities contrary to the induction loop.

The RF radio system range enables to cover important areas.
There is no obligation to install emitters only in the equipped rooms. There is no need of eye contact between emitter and receiver.


The radio transmission is used in numerous fields such as industry, telecommunication and, last but not least, television. Solutions described on this website enable to ensure an audio transmission for :

Auditive and visual accssibility in public places : theaters, cult places, stadiums, amphitheaters..etc
Guided tour : in museums, touristic centers, factories tours…etc.
Simultaneous translation : conference rooms, theaters and auditorium.

Some applications can even be combined : a conference room can be equipped with a simultaneous translation system and ensure auditive accessibility in every languages or use a dedicated channel for hearing-impaired people.

Interest : Contrary to a fixed induction loop system, the radio transmission system will be easier to implement in an existing building.

Still need help? Send us a note!

ZI Lagrange II, 9 Chemin de la vieille Ferme,
33650, Martillac, FRANCE
(+33) 09 81 24 00 06