There is a very simple process to establish whether a hearing aid has an active telecoil program, and it can also be used to check whether the program is working in an aid you know has this feature:

• Listen to the aid via a stetaclip and scroll through the programs (or switch to ‘telecoil’ if you know the program is there).
• At the same time, hold a battery-powered analogue watch to the case of the aid and you should hear a distinct ticking sound.
• This obviously does not provide a scientific check of the telecoil performance, but it does let you know whether it is working – or if the aid does, indeed, have a telecoil program activated.

This little dodge works with 98% of battery powered analogue watches, so just make sure that your watch is not one of the other 2% by trying it with a known working aid (with telecoil) initially.