A t-coil, or telephone coil, is a small copper coil in most hearing aids that picks up a magnetic field from the loop and converts it into electrical energy. This is similar to how a microphone converts sound waves in to electrical energy. By switching the hearing aid to the “T” position, the electromagnetic field is detected. The strength of that field depends on the size of the t-coil, energy or power of the magnetic field and the relative positions of the t-coil. For telephone usage, the t-coil is best when horizontal relative to the phone receiver; however, the best reception for loops is a vertical orientation. So many audiologist set the t-coil at a 45 degree angle to work with both the telephone and induction loops. It is very important for your audiologist to take as much time programming and evaluating the t-coil as the microphone for optimal satisfaction of the user. An M/T position on the hearing aid allows the wearer to hear through the t-coil but also hear through the microphone, which is preferred by some so they can hear the person next to them or others in the room in addition to the direct signal from the loop. A manual “T” or “M/T” switch is a must to allow the user control over the programs.
Be advised that many hearing aids are fitted with a t-coil but the audiologist may not have activated the program or the volume may be set very low and need to be adjusted to hear satisfactorily through a loop. Some hearing aids that do not have a t-coil may be retro-fitted to experience the clear sound through loop in your home or in public venues.