hearing aid.. what's the system called that you could have installed...

[lunavix]

Like they have in the shops? Something about tuning your hearing aid in?

Induction loop? They have them in theatres, too.

yes, induction loop.

Is it for use at home or school? There are a number of bits of useful kit out there - what specifically do you want it to do? I've got a catalogue for connevans (who provide loads of hearing equipment I could look up for you)