WHICH MICROPHONES SHOULD I USE FOR HEARING AUGMENTATION? Definition Hearing Augmentation can be any one of the following: - Hearing Loop System - FM system - Infrared System These systems typically connect to the output of an existing PA/Sound system/sound source. Alternatively, wireless microphones, TVs or music sources can be connected directly to the Hearing Augmentation System. As with all systems, the old adage GIGO applies, meaning Garbage In, Garbage Out. When microphones are used as the input source, either through a sound system, or directly into the Hearing Augmentation System, it is vital that the most suitable microphone is used for the situation, and that it is used correctly. This avoids the distractions caused by audible garbage. Most Common Mistake The most common mistakes are for installers to place ceiling microphones above the people speaking and placing a microphone in the middle of the table. Both of these methods defeat the purpose for which a hearing Augmentation System has been installed. This also has the side effect of making the system unfit for use, and being open to an indefensible DDA (Disability Discrimination Act) Complaint. Purpose When listening to a sound system, sound from the speakers reverberates off all surfaces in the environment, resulting in blurred sound for hearing-impaired users caused by these multiple reflections. Hearing Augmentation is installed to allow the hearing impaired user to hear as if they were less than one metre from the sound source, with no background noise. This is achieved by removing both background noise and reverberation. Rev 2.0
This results in the user receiving the clearest possible sound to their ears, via hearing aid(s) and/or cochlear implant processor(s). Misuse of the sound source or microphones results in degradation of the signal, rendering the Hearing Augmentation System useless. Microphone Types The different microphone types are referenced in AS 1428.5-2010, together with maximum distances for use with Hearing Augmentation Systems. Some people assume that microphones are as efficient as the human ear, which is not the case. An excellent example is the humble, handheld microphone the microphone sounds different when held close to the mouth, when directly under the chin, or when further away. Generally, if the handheld microphone is any more than 100mm from the mouth, it sounds tinny or flat and this degrades the signal. The appropriate distances as listed in AS 1428.5 2010 are: Hand-held less than 100 mm. Gooseneck directional 300 mm to 600 mm. Boundary microphone 150 mm to 500 mm. Any other microphones are assumed to handheld. Please note that the distances listed are absolute maximums. Shotgun Microphones For Hearing augmentation purposes, shotgun microphones are only to be used for live performance spaces. Shotgun microphones are a special case, as they are designed for recording from a distance, and the directionality applies at higher frequencies much more than lower frequencies. Consequently, for hearing augmentation systems, a much more directional shotgun microphone is required than that used for recording or for back of house in performance spaces. This issue is particularly critical, but mostly overlooked. Often these microphones are chosen to suit people with normal hearing and for purposes other than what is optimal for the hearing impaired. Microphones of lesser standard than specified above defeat the purpose of Hearing Augmentation.
The microphones must have a polar pattern equal to or better than -2.5dB (at 1kHz) at 30 degrees off-axis and be situated on the side walls of the thatre, no more than 8 metres from the stage, on both sides. Lapel Microphones Lapel microphones must be worn around the neck area, and directed at the mouth. These microphones may be directional which is why pointing them at the mouth is important. Some users clip the microphone where a tie clip may go, or even lower this results in poor sound quality. Testing It is important that when testing the system, both for level and clarity, that all microphones are used in the way they will be in real life. Conclusion: People with hearing loss require Hearing Augmentation to increase speech intelligibility by reducing the background noise along with the reverberation. This means that the most suitable mic must be used, and must be used correctly. References BCA / Disability (Access to Premises - Buildings) Standards 2010 DP9 The Performance Requirement of DP9 states: An inbuilt communication system for entry, information, entertainment, or for the provision of a service, must be suitable for occupants who are deaf or hearing impaired. D3.7 states the deemed to satisfy provision for DP9. D3.6 states the signage requirements. AS1428.5 2010 Communication for people who are deaf or hearing impaired Clause 4.8 4.9
Articles Other articles are available at: https://printacall.com.au/links/ Newsletter These articles are emailed out approximately every two months. Sign up to receive new and updated articles at: https://printacall.com.au/hearing-augmentation-newsletter About the Author Andrew Stewart is qualified in electronics, and has been working for Printacall Communications Technology for over 30 years of installing, testing and commissioning Hearing Augmentation Systems. He and his team have conducted their own research of comparison methodologies of installing hearing loop systems and designed and constructed test equipment. Installations include Sydney Opera House, First Class Qantas Club Singapore, art galleries, museums, theatres and many others. Andrew was a key leader in the development of AS 1428.5-2010, the authoritative document on Hearing Augmentation in Australia. He is also a life member of Deafness Forum of Australia (the peak body for hearing impaired people in Australia) and continues to represent them, as he has on many committees for over 15 years. Andrew has been hearing impaired all his life, with a progressive loss, and now wears two cochlear implants. He has 9 other family members who wear hearing aids and or cochlear implants. Why choose Printacall Communications Technology? Specialising in Hearing Augmentation Systems for over 30 years. I nnovative technical team who conduct research and development of our Hearing Augmentation systems for improved outcomes. ver 30 years of design, installation and commissioning of Hearing O Augmentation systems (loop systems, FM systems, sound field systems and public address systems) for a range of public access buildings, for small halls to significant buildings and venues.
R efer to our past work link on for a sample of completed jobs. Hearing Augmentation seminars for building professionals. P rovide training in Hearing Augmentation for Access Consultants, Building certifiers and surveyors, and architects. heck our Hearing Augmentation Articles for professionals C at https://printacall.com.au/links/ Legal The information provided is general advice only and does not take into account your building site objectives, building site design and or building materials used or other relevant factors and cannot be relied upon for your specific needs therefore Printacall Communications Technology, its directors, agents and or employees do not accept any liability or responsibility arising in any way from the use of the information provided. The information should not be relied upon for accuracy or completeness. Further information If you have any questions, email Andrew Stewart at astewart@printacall.com.au