Definition of Hearing Augmentation and Hearing Augmentation Options
Hearing augmentation can be defined as the communication of information for people who are deaf or hearing impaired by using a combination of audio, visual and tactile means. Hearing augmentation system options to comply with the ‘Deemed-to-Satisfy’ provisions include:
- Audio frequency induction loop systems (hearing aid T switches can be used, or receivers provided to those without a T switch on their hearing aids).
- Frequency modulation (individual receivers worn by users to receive radio waves (i.e. a FM transmitter / receiver systems)).
- Infra-red (transmitter / receiver system, where individual receivers are worn by users to receive infra-red beam by a direct line of sight).
Intent of the BCA Hearing Augmentation ‘Deemed-To-Satisfy’ Provisions
The provision of an effective hearing augmentation system is aimed at assisting people with a hearing impairment to access communications associated with a building’s use.
A hearing augmentation system installed under the ‘deemed-to-satisfy’ provisions of the BCA will cater for people with moderate to severe hearing loss, but would not cater for all people who are deaf or hearing impaired. For example, a prescribed hearing loop system under the BCA would be of no benefit to people with profound hearing loss or people who are deaf.
The design of a system within any building needs to ensure that people who are hearing impaired, with moderate to severe hearing loss, are able to have any communications transmitted through the inbuilt amplification system relayed and amplified to them through the proposed hearing augmentation system.
Hearing Augmentation System Requirements
Hearing augmentation systems must be provided where an inbuilt amplification system is provided (other than one only used for emergency warning). They are required in the following locations (BCA Clause D3.7(a) and Premises Standards Part D3.7(1)):
- in a room in a Class 9b building (that is an assembly building such as a school, university or trade workshop)
- in an auditorium, conference room, meeting room, or room for judicial purposes, and
- at any ticket office, teller’s booth, reception areas and similar areas where the public is screened from the service provider.
It is important to note that if there is no inbuilt amplification system in a room then a hearing augmentation system is not required by the BCA or Premises Standards.
Coverage of Hearing Augmentation Systems
Where an induction loop is provided, it must cover at least 80% of the floor area of the room or space that is served by the inbuilt amplification system (BCA Clause D3.7(b)(i) and Premises Standards Part D3.7(2)(a)). For hearing augmentation systems using audio receivers, such as IR or FM transmitter / receiver systems, the system must cover at least 95% of the floor area of the room or space served by the inbuilt system, and a minimum number of receivers must be provided in a ratio depending on the number of people who may be accommodated in the room (BCA Clause D3.7(b)(ii) and Premises Standards Part D3.7(2)(b)).
Number of Receivers Required (IR and FM Systems)
Receivers to be provided in the following ratios (BCA Clause D3.7(b)(ii) and Premises Standards Part D3.7(2)(b)):
|No. of occupants in room or space||No. of receivers required|
|Up to 500||1 receiver for every 25 persons or part thereof, or 2 receivers whichever is greater|
|More than 500 persons, but not more than 1,000 persons||20 receivers, plus 1 receiver for every 33 persons or part thereof in excess of 500 persons|
|More than 1,000 persons, but not more than 2,000 persons||35 receivers, plus 1 receiver for every 50 persons or part thereof in excess of 1,000 persons|
|More than 2,000 persons||55 receivers, plus 1 receiver for every 100 persons or part thereof in excess of 2,000 persons|
Clause D3.6 of the BCA and Part D3.6(a) of the Premises Standards requires Braille and tactile signage must identify a room or space with a hearing augmentation system, identifying the type of system, the area covered and if receivers are being used, where the receivers can be obtained (BCA, Clause D3.6 (b)). The signage must also include the International Symbol of Deafness in accordance with AS1428.1. Signage must identify the following:
- Type of hearing augmentation system; and
- The area covered within the room; and
- If receivers are being used and where the receivers can be obtained.
Selection of a Suitable Hearing Augmentation System
Although the BCA and Premises Standards includes a number prescriptive parameters for the installation of a hearing augmentation system, it unfortunately does not consider a number of critical factors, such as sound reverberation and the acoustic quality of finishes, background noise, sound source distances, volume and shape of rooms.
This is a significant factor to the ability to provide an effective system within large open spaces such as sports stadiums. It is also important to consider the specific use and layout of the building to determine suitable hearing augmentation systems. There are buildings that have been built to meet the ‘Deemed-to-Satisfy’ provisions of the BCA, but the final installation may not be appropriate for people who are hearing impaired (e.g. installing a hearing loop system within a large public hall with poor acoustics may not be effective).
Factors to Consider when Selecting a System
Given there is a wide range of different hearing augmentation systems available the decision on which type of system to use will depend on a number of factors, such as the size and use of the space, external interferences and building materials used. There is also a lot of new technology emerging in the area. Hearing augmentation is not required under the BCA to cover 100% of the floor area of the spaces they serve as such coverage could spill over into adjoining rooms and affect the operation of any system installed in those rooms.
Additionally, design considerations such as interference and room layout mean that it is difficult to ensure complete coverage in achieved in any room. When considering the suitability of an induction loop system it is important to note that the spill-over of the signal of any induction loop system can occur for up to 10m outside the designated coverage area.
Portable infra-red systems provide the ability to position the portable device in direct line of sight within each room or space served by the portable infrared transmitting device and thereby reduces any potential of the spill-over or leakage of transmissions interfering with an abutting room also served by a similar system.
Conversely, the spill-over of an FM transmitting system can occur for some distance (AS1428.5, Clause 4.3.7), however, if there are different frequency zones within the FM range, this would not be a foreseeable problem and the benefit of zoning each area offsets this issue.
The use of portable IR systems provides the ability to position the portable device in direct line of sight within each room or space served by the portable infrared transmitting device and thereby reduces any potential of the spill-over or leakage of transmissions interfering with an abutting room also served by a similar system.
The ability to reduce spill-over of the transmission of amplified conversations over multiple hearing augmentation systems (or adjoining levels within a building or city area, given the potential leakage range) is also assumed to be an important factor for selection given there could be sensitive discussions being undertaken within rooms.