Accessibility at NSW CLIC

• Induction plate
• Neck Loop
• Audio Shoe
• Magnetic Field Loop
• Loop Receiver
• FM Systems
• Infra-red Systems

Induction plate (small personal loop system)

Description

An induction plate is a thin, hook-shaped plate attached to a cord with a 3.5 mm or 2.5 mm plug at the other end. Induction plates may be used with one hearing aid (monaural) or with two hearing aids (binaural). The plate is hooked around the ear, near the hearing aid (which must have a T switch). Induction plates do not work with in-ear aids. The plate can be connected to any earphone outlet. It could, for example, be connected directly to such sound sources as a radio or television. Alternatively, it can be connected to an or infra-red receiver. The user is then much less constrained, as a direct cable connection to the sound source is not required.

Advantages

The induction plate transmits the sound from the amplifier directly to the telecoil (receiver) in the hearing aid. By using an induction plate and a hearing aid with a T switch, the hearing impaired person hears the sound from the sound source such as radio, television, telephone or tape recorder with no reduction in loudness caused by distance and no interference from background noises. As discussed above, the induction plate may be used with specialised equipment such as FM and infra-red systems. This can be valuable in lecture situations. A person using a hearing aid in each ear, together with an induction plate for both, can adapt these to listen to stereo material by using a purpose-made connection (Deafness Resources Australia can assist).

Disadvantages

Care must be taken to place the induction plate very close to the hearing aid. The plate may be uncomfortable to wear. The fine connecting cables require careful handling to avoid breakage.

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Neckloop

A neckloop is a loop of cable which is placed over the head to rest on the shoulders and is connected by cable to any device which has an earphone socket. When the hearing aids are switched to T position, a clear signal is heard. That is, a neckloop serves a similar function as an induction plate.

Advantages

These are similar to advantages of induction plates discussed above. In summary, the user can concentrate on a sound source without interference from other sounds. The neckloop is more robust and easier to use than induction plates.

Disadvantages

Both channels of a stereo signal are sent to each hearing aid if two aids are used-that is, the stereo effect is lost.

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Audio shoe

Description

A limited number of hearing aids have this facility. A small socket is located on the aid, to which a cable can be connected. The other end of the cable can be directly connected to appliances such as televisions, tape recorders, etc, as discussed above. Some hearing aids permit a proportion of ambient sound to mix with the selected source, whereas other types allow only the selected sound to be heard.
Advantages
The hearing aid receives the sound via a direct connection to the appliance. This improves sound quality.

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Magnetic-field loop

Description

This consists of a loop of cable, within which is created a magnetic field by electrical current produced from a microphone and amplifier. When switched to the T position, hearing aids within the range of the loop will respond with a clear, strong signal. Loops can be placed so as to cover large areas such as an auditorium or in small scale in the earpiece of a telephone.

Installation of a loop does not always have to be on a permanent basis. At a multi-venue site, such as a school, effective and economic use can be made of temporary loops. The loop cable may be laid on the floor, along skirting board or wall or attached to the ceiling, provided it is not more than three metres above the floor. To avoid accidents, loop cables should be taped across doorways or passageways or, alternatively, taken up and over the door frame.

Where an induction loop is installed, the magnetic field strength and frequency response should conform with the requirements of Australian Standard (AS) 1088.4 1987 Part 4. Where an induction loop has been installed in a venue, it is necessary that appropriate signage, conforming to international standards, (AS1428.1 refers.) be provided so that persons using the venue are aware of the existence of the loop. To ensure the effective operation of a loop in a venue, it is essential that the lecturer using the venue is able to operate the loop. This usually requires only a notice beside light switches to identify the loop power switch and to remind of the necessity to switch on the loop. Usually there is no adjustment required to the loop amplifier when it has been set to meet the requirements of the standard. In order to ensure that the loop is operating satisfactorily, it is necessary for the proprietor of the venue to have available a loop receiver.

Advantages

An installed loop is a valuable resource in buildings where public gatherings will be held. This includes lecture halls, particularly those where ambient noise from adjacent rooms intrudes or where echo is a feature. A person with a severe hearing loss can hear proceedings, either by using a hearing aid with a T switch or a loop receiver.

Disadvantages

In settings where highly confidential issues are to be discussed, use of a loop can pose a security risk. In some circumstances, there can be “spill” from the looped area. That is, signals from a loop can be received a little beyond the area it covers and, hence, in an adjacent room. The signals may also be received on the floors above and below the room containing the loop.

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Loop receiver

Description

This is a small, hand-held amplifier designed to receive signals from an induction loop. It is powered by a nine-volt battery. A socket allows the connection of earphones. A volume control allows adjustment of sound level. It is available from Deafness Resources Australia.

Advantages

In venues where an induction loop has been installed, wearers of hearing aids which lack a T switch can access the loop by using a loop receiver and a set of earphones. Persons with hearing loss, but not wearing hearing aids, can also use a loop receiver to access the loop. This can be very relevant in a lecture hall situation if the acoustics of the venue are a problem.

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FM systems

Description

In this system the person talking speaks into a microphone which is connected to a transmitter. The person with the hearing loss wears a receiver. Options for getting sound from the receiver to the ear depend on the degree of hearing loss and personal preference. They include induction plate, audio shoe, neckloop or headphones or, as in one example, via loud speakers. A wide range of configurations is available, to suit very diverse personal and environmental circumstances.
Advantages
The user is provided with clear, high-quality sound over a considerable distance. There is much potential for benefit in a lecture situation.
Disadvantages
There is the need for more hardware than with a conventional aid. It is also possible that some people-both hearing aid users and those required to use the transmitter-may feel uncomfortable about using it. Care must be taken by the speaker to ensure that the microphone does not rub on clothing and therefore cause interfering noise. Because the transmission can extend beyond the room in which the equipment is used, a security risk similar to that discussed in relation to loops exists. For a similar reason (transmission going beyond the room), problems can occur if more than one FM system is used in a school or college situation. If signals from two or more systems overlap, a listener will be unlikely to make sense of the information. In settings where two or more concurrent sessions in close proximity are likely, it is necessary to purchase units on different frequencies or to use the more sophisticated (and costly) multi-frequency receivers which can be user-adjusted.

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Infra-red systems

Description

As with FM systems, the person talking speaks into a microphone which is connected to a transmitter. The person with the hearing loss wears a receiver, which is powered by rechargeable batteries. Options for getting sound from the receiver to the ear depend on the degree of hearing loss and personal preference. They include induction plate, neckloop, audio shoe or headphones. This equipment can be established at two levels-one for individual use and one for large venues. In most circumstances, the cost, both in terms of initial layout and ongoing administration, makes this option not viable in large venues. For individual use, however, it can work well in a setting such as home and in small lecture rooms.
Advantages
Clarity of signal is potentially very good. The system is especially effective for receiving sound from stationary devices such as televisions. It is also very useful in venues such as cinemas, where necessary hardware can be installed. In circumstances where security is important, the line of sight transmission ensures that the signal cannot be received beyond the room where the equipment is established.
Disadvantages
Cost is high for large venues. This is because all equipment has to be provided by the proprietor and entails ongoing costs related to maintenance of batteries, hygiene and security. In a large venue such as a lecture hall, people moving between the speaker and listener may (but usually would not) interfere with the line-of-sight transmission of the infra-red signal. The system is mains powered, limiting mobility of the speaker.

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