Audioloop (or some times just "loop") refers to an Assistive Listening System that consists of microphone(s), an amplifier, and a loop of wire that goes around a room or part of a room. The sound is amplified, not to audio speakers, but into the loop of wire. This sets up a magnetic field that can be detected by receivers and some hearing aids that contain a telecoil.
Many SHHH chapters use a loop at their meeting so that people attending can switch on the telecoils in their hearing aids and hear the meeting well.
While the word audioloop typically refers to an entire system including the amplifier, mics and loop, itself, for an entire room or area in a room, the same technology (magnetic signals representing sound) is frequently used in personal Assistive Listening Devices where a neckloop or a silhouette is used as the "user interface" to your hearing aid's telecoil.