Assistive Listening Systems
Generically referred to as induction loop systems, this is incorrect as inductive loops are only one of the technical solutions available. In essence these systems allow sound (speech and music) to be transmitted directly to a hearing aid wearer.
Assistive listening systems are often specified and installed by people with little or no knowledge of relevant technical design and without the specialist test equipment to setup an effective installation. This leaves many induction loop systems completely ineffective, or providing uncomfortable levels for hearing aid users. Deaf Alerter plc offer a remedial engineering service to correctly set up such installations, as unfortunately we often find that the wrong equipment has been installed.
There are two technologies available:
Induction loops
This system transmits sound to a hearing aid's Telecoil via a magnetic field created by the induction loop. In this way only sound fed directly into the induction loop (through a microphone for example) will be picked up by hearing aid users using the "T" Position. (note not all hearing aids have this facility). Any number of people within the loop's field can receive the transmission; making it a low-maintenance, cost-effective solution to obligations under the DDA and other legislation. Thought has to be given to the nature of information being transmitted by induction loops, as magnetic field overspill is almost inevitable, meaning that ‘eavesdropping’ is relatively easy whether on purpose or accidentally.
Types of Induction Loop Systems
• Counter Loops: the counter loop is designed to facilitate the communication between two people; a hearing person and a hard of hearing person at a fixed location. A wire loop is normally fixed out of sight to the underside surface of the desk or counter with adhesive or clips. The loop is connected to a small amplifier (typical size 216mm x 124mm x 44mm) which is powered from an adjacent standard 13A mains socket. A small microphone is normally fitted to the underside of the counter pointing towards the face of the operative working at the counter. Again, this is normally installed so it is not visible from the front (customer-facing) side of the counter. Ideally, the loop needs to be positioned away from computer screens and other electrical equipment that can cause a “hum” on the audio.
• Portable Loop: the portable loop is designed to facilitate the communication between two people; a hearing person and a hard of hearing person, but can be moved from location to location. It is a battery powered unit with a mains charger incorporating a microphone, amplifier and loop.
• Room Loops: the room loop is designed for a fixed location and will provide assistive listening for as many hearing aid wearing people that can fit in the room. The loop cable/tape can either be installed on the floor (typically underneath the carpet) or in the ceiling. It can also be run around the skirting board of a room, however special protection is required at door entrances. Connected to the loop will be a loop driver/amplifier (model determined by size of room) and a source of audio e.g. microphone / mixing desk.
Infra-red
Infra-red systems comprise of two components; the sender and the personal receiver. In larger rooms multiple senders will be required. The sender is connected to the sound source (e.g microphone or mixing desk) and located to be visible by the hard of hearing people. It communicates the sound information via an infra-red signal to the personal receivers worn by each hard of hearing person. The sound is then provided either directly via a headset or into their hearing aid via an inductive coupling.
Comparative Benefits
The advantages of inductive loop technology are:
- the user only needs their hearing aid
- easy to use in across counter situations
- no problems associated with handing out and collecting loan equipment
The advantages of infra-red technology are:
- ease of installation
- audio quality
- easy to setup a portable room system
- people without inductive coupling hearing aids can use a stethoset headset receiver
- Infra-red systems do not suffer any “over spill” problems outside of the room the system is covering
- Ideal for confidential environments
- Easier for flexibly partitioned room
Types of Infra-Red Systems
Personal Systems
The personal infra-red system uses a low power infra-red sender that can be used with audio sources such as a bedroom television. They can also be used in a one to one conversation situation with a built in microphone. Easy to adjust user controlled volume level.
Portable Room System
Portable infra-red room systems are ideal if you wish to share a system between several rooms. The complete system fits in a briefcase and can be set-up in a matter of minutes. A compact sender unit can be placed on a small stand or desk pointing towards the audience. A range of microphones are available (including radio and boundary types) other audio sources including music can be connected. One or more infra-red receivers can be used with this system.
Permanent Room System
A permanent infra-red room system has wall mounted sender(s). The size number and location of these senders are based on the characteristics of the room. A range of microphones are available (including radio and boundary types), other audio sources, including music can be connected. One or more infra-red receivers can be used with this system. This system will not cause overspill outside of the room.
