by Neil Bauman, Ph.D.
A man reported,
I have tried FM systems in different locations with marginal to no success. In the rooms that I could not successfully hear, it was due to the FM system picking up electrical impulses in the walls as well as from the florescent light fixtures. This interference was much louder than any voice signal.
FM systems, by themselves, do not pick up electrical impulses (actually a varying magnetic field) from current flowing though the electrical wiring in the walls or from florescent light ballasts. It is the t-coils in your hearing aids that pick up these buzzing or humming sounds.
The reason you were hearing buzzing via your FM system and hearing aids is because you were using a neckloop to connect your FM system to the t-coils in your hearing aids. As a result, you had your hearing aids in t-coil mode. Your t-coils were picking up the buzzing, not the FM system itself.
To prove this, just switch your hearing aids to t-coil mode and listen without using any assistive device. If magnetic interference is present, you’ll hear it. Next, take your hearing aids off and use the FM system by itself with earbuds or headphones and you’ll notice you hear beautiful clear speech without any interference.