Magnetic induction is a simple tried and tested technology that works by transmission of signals in the form of a magnetic field. You can receive these signals by setting your hearing aid(s) to 'T' - provided they incorporate this useful feature. In this system, the input signal from a microphone that is picking up sound. a television, or some form of recorded music, say, is fed to an induction loop amplifier. The output current from the amplifier is then fed into a loop of wire that is installed around or close to the listening position. A 'loop' may be of sufficient size to cover a complete auditorium, or may be fitted just around a ticket office counter for example.
Small, self-contained portable loop systems are also available. You simply place the unit close to where you want to listen (to efficiently couple to our hearing aids).
Even smaller personal induction loop systems that you can wear form useful listening accessories.