By Dr. Noël Crosby, Au.D.
Another great resource for hearing aid users are hearing loop systems. The technical name for these systems is Audio Frequency Induction Loop System. In its most simple form, this system utilizes a loop of copper wire around the perimeter of an area that is connected to an induction hearing loop amplifier. A looping system allows the sounds coming from a public address system to be received directly to hearing aids that have a T-coil. This technology expands the functionality of the hearing aids and picks up all the sounds coming from the stage. Always look for this symbol. If you don’t see this symbol you should ask if a looping system is present.
What is a telecoil? A telecoil is just a tiny coil of wire inside your hearing aid that picks up electromagnetic signals given off by various devices including loop systems and telephone handsets. The loop wire is the transmitting half of the loop system. The receiving half is the telecoils in your hearing aids. There are a variety of names by which people refer to telecoils. They may call them T-coils, T-switches, telecoils, telephone coils or audio coils. It doesn’t matter. All these names refer to the same thing—a tiny coil of wire in your hearing aid. In order to use a loop system, you must have hearing aids equipped with telecoils. Unfortunately, a good number of hard of hearing people do not even know if their hearing aids have telecoils installed or not. When purchasing a hearing aid you should insist that it has a telecoil. Telecoils got the name “T-switch” from the switch on the analog aids that typically switched between “M” for microphone, and “T” for telephone. Now, it is your hearing aids’ job to convert this magnetic signal into sound you can hear. When you switch your hearing aid from its microphone to its telecoil, all you are doing is connecting a small coil of wire to the input of the hearing aid’s amplifier instead of its microphone. This tiny coil of wire is sensitive to nearby magnetic fields such as the one produced by the loop system. The changing magnetic field in the room loop induces a corresponding electrical signal into the telecoil. The hearing aid amplifier then amplifies this signal and you hear a faithful reproduction of the original speech signal. This technology works better than Bluetooth technology because there are several factors that act as limitations to Bluetooth.
First, Bluetooth is not built into hearing aids (it’s in the remote) because it uses too much power and drains the hearing aid’s batteries too fast. You must have a remote with you in order to use Bluetooth with your hearing aids. In contrast, t-coils don’t use any extra power, and don’t require any extra items to be hung around your neck in order to use them either.
Second, Bluetooth was designed to be paired with one other device at a time for privacy issues. For example, no one could connect to, and overhear, your phone call. If Bluetooth were provided, only one person in the entire church or meeting could pair to the Bluetooth system; this would leave all the other hard of hearing people without any help. In contrast, as many people with t-coils in their hearing aids as can fit into the looped room can use a loop system at the same time.
Third, Bluetooth has a very limited range. The theoretical limit is 33 feet. Thus, in a large room, unless you sit within 20 to 30 feet of the Bluetooth transmitter, you will not be able to hear. A loop system allows to you sit anywhere in the looped room and hear wonderfully well.
Two other types of listening systems are Infrared and FM. The US has chosen to use more Infrared and FM systems, while Europe has been using loop technologies for 40-50 years; however, there are disadvantages to using Infrared and FM systems: both systems require the use of a special headset; neither are compatible with hearing aids. Infrared suffers quite badly from shadowing, this means that the signal is lost when there is no direct line of sight from the receiver to the transmitter. FM’s suffer from loss of signal and privacy issues. FM also requires a different frequency for each venue, this means that a different headset is required at each location. These systems require the use of a headset; this makes it obvious that a person needs assistance. Sound may leak out of the headset and disturb others around the wearer.
The most important aspect of a Loop System for a hearing instrument user is the fact that they can continue to wear their hearing instruments and have the sound broadcast directly into their ears. Hearing aids have a prescriptive value and are programmed to allow the wearer to have clearer hearing. The hearing aid delivers customized sound to address a persons own unique hearing loss. If a person has to remove them to wear a headset, they lose that prescription. It would be like taking off prescriptive eyeglasses to wear non-prescription sunglasses.
There is a website that that you can visit that will let you enter a location and it will find which venues are looped near that location. This website is http://www.aldlocator.com.
Coming Next Month: Hearing Resources Part 3: Brain Fitness & Local Support Groups.
Dr. Noël Crosby, Au.D., owner and practicing audiologist at Advanced Hearing Solutions in Englewood, FL is an experienced professional whose career has been devoted to helping people of all ages hear and understand more clearly.
With over 23 years of experience, Dr. Crosby’s career path is marked by the pursuit of advanced education. After completing her undergraduate requirements, she received her Bachelor and Master of Science degrees from Florida State University and her Doctorate in Audiology from the University of Florida.
Her credibility as an authority grew during her tenure as the Director of Audiology at the Silverstein Institute in Sarasota, FL from 1991-1998. Today, in addition to managing a successful audiology practice, Dr. Crosby just completed her second term as president of The Florida Academy of Audiology.
941-474-8393 | www.drnoelcrosby.com