Induction Loop Systems
What is Assistive Listening
Assistive Listening Devices, often referred to as ALDs, are technologies that assist the hearing impaired members of society who struggle to hear properly in busy or noisy environment, or in situations where there is a significant distance between themselves and the sound they wish to hear.
Assistive Listening Devices function by capturing a desired sound source and transmitting it directly to a receiver that in-turn delivers it directly to the user’s ear, without background noise, interference or distortion. The three main technologies utilised to perform this task are Audio Induction Loops, Infra-Red and R.F. (radio frequency).
In many countries around the world legislation has been put in place stating that ALDs are now legally required by in any public place where it is important that a hearing impaired member of society is given the same opportunity to hear messages, speakers, or any other sound as clearly as anyone else. Examples of this legislation can be found in national building codes and ant-discrimination laws such the UK Equality 2010, Americans with Disabilities Act 2008 and Australia’s Disability Discrimination Act.
To ensure that Assistive Listening Devices function as they are intended to, providing a genuine benefit to the hearing impaired users, internationally governed Standards of operation have been created (such as EN60118-4: 2006, which dictates induction loop operation).
These Standards not only ensure quality, but also actively discourage facility operators from installing low systems which do not function as intended in an attempt to comply with legislation whilst reducing costs.
The three main assistive listening technologies (audio induction loop, infra-red and R.F.) each have both positive and limiting factors which may or may not suit a specific application.
Ampetronic believe that induction loops provide the best all-round assistive listening solution. This opinion is shared by most knowledgeable installers and venue operators and he led to induction loop becoming the default solution in most countries.
Ashton Audio can consult, design and install your Assistive Hearing solutions
A Comparison of Assistive listening Technologies
For the end user (hearing impaired individuals)
Provides direct sound
Uses hearing aid for optimised sound (without additional neck loops)
No receivers (simple, hygienic)
Discreet (no discrimination)
Doesn’t require line of sight
Suitable for ‘transient’ use (e.g. transport & retail)
For the service provider, venue operator or specifier
No receivers (major cost saving)
Doesn't require building modification
No licensing required
Can be confidential (not received outside intended area)
Suitable for 'transient' use
Doesn't require line of sight
Isn't affected by daylight or windows
Induction Loop Systems are solutions for assistive listening, providing access to high quality intelligible sound for the hard of hearing. These systems are a great benefit to the hard-of-hearing, and the demand for them is rapidly increasing around the world:
- Assistive listening benefits a large and ever growing section of society - hearing impairment affects one in seven of us, a number that is increasing as the population ages. Providing fair and high quality service to this large group is becoming a high priority for any service provider or public organisation.
- Induction Loop Systems offer many unique benefits to service providers and to end users that make them an essential facility in many private and public environments. Legislation is in force or in development in most western countries to mandate the use of Induction Loop Systems and ensure that this benefit is given to the hard of hearing. The adoption of the technology is becoming rapidly more widespread around the globe.
- The hard-of-hearing community is increasingly aware of the solutions available to assist them, increasing end-user demand for assistive listening solutions.
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.
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.
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.