It is also known as an Induction Loop because it works on the induction principle.
Hearing aids that have the Telecoil feature can receive sound signals directly from an audio loop without needing a separate receiver. This makes this kind of ALS particularly attractive since cumbersome and often expensive receivers and neckloops are not needed.
The next page explains the induction principle in simple terms for a layman, not an engineer or a scientist. Later pages will include information on where to purchase complete systems and information for DIY (do-it-yourself) audio loops.