Infrared does have the specific advantage that it can be in multi-channel systems for simultaneous translation, purely as a communication system. Infrared also provides a signal does not travel through walls, providing confidentiality. Induction loops can also provide confidentiality utilizing specially designed low spillover loop configurations.
Infrared suffers from "shadowing", resulting in the lost of signal in areas of the room that are not in the line of sight of the infrared emitting panels. This has implications to the interior finishing options of the area where an infrared system will be used.
FM systems are even less attractive. Professional radio microphones operate using diversity reception to reduce signal loss due to reflection of the signals from walls, etc. Diversity reception is not possible with the FM receivers used for assistive listening. Furthermore, there is a major problem with shortage of frequencies and confidentiality is totally non-existent.
There are significant costs incurred with passing out, retrieving, and maintaining the required receivers / headsets. Theses costs are incurred by the facility operator and unfortunately, this frequently results in resistance on their part to installing assistive listening technology.
Using a receiver / headset also draws attention to the hearing disability of the user and our experience has been that this results in decreased usage of assistive listening systems. The limited usage of assistive listening technology gives credence to the argument that "assistive listening technology is not necessary because no one uses it."
Finally, there are also serious concerns about the standards of hygiene. Have the receivers really been cleaned and disinfected after use?
Are all hearing aids compatible with Audio Frequency Induction Loops ?
While not all hearing aids are fitted with a telecoil, 90% of the hearing aids can be fitted with a telecoil. Hearing advocacy organizations, such as AG BELL and Hearing Loss Association of America, acknowledge the benefits of a telecoil and actively promote telecoil usage.We recommend the hearing aid user always discuss the telecoil option with their audiologist BEFORE purchasing the hearing aid to ensure it has a telecoil. It should be noted that cochlear implants are telecoil compatible.
Hearing aids equipped with a telecoil have a switch allowing either "M" (microphone) or T (telecoil) operation. Some models may have a switch marked MT (microphone and telecoil).
- The M (microphone) position is for "normal" listening, that is receiving airborne sound via the microphone built in to the hearing aid.
- The T (telecoil) position is for receiving the sound via induction of the telecoil, which is built in to the hearing aid.
- The MT position, which is provided on some hearing aids, allows listening simultaneously both to airborne sound via the microphone and to inductively transmitted sound via the telecoil.
What about Digital hearing aids ?
Digital hearing aids work in exactly the same way as ordinary analog hearing aids in terms of induction loop use but you must make sure that the digital hearing aid has a "T" switch position. Check with your audiologist about this before you buy. If you have a non-telecoil equipped hearing aid, ask your audiologist if a telecoil can be retrofitted with a telecoil or if the telecoil can be activated.Many digital hearing aids allow the option of setting the relative levels between microphone and "T" coil inputs to be adjusted by the audiologist. If the loop signal is quiet / loud relative to normal microphone use, ask your audiologist to adjust it for you.
Do Audio Frequency Induction Loops Interfere with heart pacemakers ?
Under normal circumstances, a correctly installed induction loop system does not interfere with heart pacemakers. A minimum separation distance of 2 inches (50mm) should be maintained between loop cable and pacemaker to remove any potential for interference.Additional information regarding audio frequency induction loop equipment and designs can be found at www.AssistiveAudio.com or
AssistiveAudio
2627 Algonquin Pkwy
Toledo OH 43606-3709
800 224 9295 (Voice)
419 473 8906 (Voice)
419 292 2169 (Fax)
About Deafness also has a general article on assistive listening devices.
