Julie responding here as I just saw this. The secret to the assistive listening devices working, is the elimination of that background noise. Sound comes through a microphone in the speakers presence (the closer to the mouth the better), and is sent wirelessly to the hearing aids that a person is wearing. The desired sound bypasses all the ambient noise. The hearing aids must be equipped with a component that can receive the signals from the speaker's microphone. That's what hearing loops, FM systems and Infrared systems do. BlueTooth can also send signals wirelessly over a distance, however, A BT microphone can only transmit to the hearing aid that it's paired to. A mike that is connected to the public address system in a venue, allows those other systems to transmit to as many hearing aids equipped with telecoils that are being used in the venue.
It's hard to understand the value of this equipment without being able to try it. Ask your audiologist to demonstrate how telecoils work. You'll be amazed. Julie PS: Don't let them tell you it's outdated, old technology. Plus it adds zero cost to a hearing aid.