Your Audiology Tutorial: T-Coils

Telecoils ("T-coils") are tiny copper coils found in some hearing aids and cochlear implants.  The T-coil has long been implemented to assist patients' use of landline telephone phones.  The electromagnetic field around a telephone receiver would often cause interference with a traditional hearing aid microphone array and T-coils would kick into a separate mode, actually using the magnetic field to promote the signal.  T-coils can also interface with other assisted listening devices.

In recent years telecoils have received more attention for their success in "looped" areas - rooms fitted with induction loops (current is "induced" in the telecoil via the electromagnetism).  Theaters, lecture halls, and churches are increasingly fit with hidden copper wire or tape to allow hearing aid users to access the signal free of background noise so common to omni directional or directional microphones in amplification (some devices do allow simultaneous use of mics and T-coil).

FM systems are still common in such places but T-coils are less hassle as the former requires the user to wear a device that may not be the most comfortable (or hygienic).  FM also requires frequency transmissions specific to each location.  Someone wearing hearing aids equipped with a telecoil can use the same technology anywhere a room is looped.

Note that your hearing aid(s) must have a manually accessible (via switch on device or option on remote control or smartphone app) T-coil memory/program in order for its use in looped areas.  Some aids are programmed to have the telecoil activate automatically when phone is brought within ~3 inches of device.  Talk to your audiologist or dispenser.