[zaarn]

When I studied at Uni, some lecture halls had induction, where the sound recorded by the microphone would be transmitted via an inductive system throughout the entire room and compatible hearing aids would be able to use that sound instead of having to boost the audio from the speakers throughout the hall.

[jrace]

That is input via induction (there is also FM and BT transmitters)

The GP was referring to induction output - of which comprises a minority of hearing devices.