Loop systems work along the lines of FM, and the sound is delivered directly into the T-Coil of each hearing aid that has one built in. It's quite interesting, and this is why I'm working on getting a new pair hearing aids.
When we were visiting Rochester Institute for the Deaf, I noticed signs around rooms that had the loop icon.
I love that this is something that is now advertised and visible to the public and that more and more cities are using this technology.
This video simulates the difference of having a loop system, versus one without. There will be no captions at the beginning, so that those who can hear, can experience what it is like for a person with deafness or hearing loss or someone with hearing aids where there is no loop. To add captions would be, as they pointed out at the end of the video, "unfair".