telecoils

Telecoils, or T-coils, are small coils of wire embedded in many hearing aids and cochlear implants. They detect the magnetic field produced by nearby induction loop systems and convert it into an electrical signal that the device can amplify and deliver to the ear. Using a telecoil can improve speech understanding in certain listening environments by bypassing ambient noise.

How they work: An induction loop installed around a room, a seating area, or a vehicle carries audio from a source such as a public address system. The loop generates a changing magnetic field corresponding to the sound. The telecoil senses this field and the hearing aid processes and plays the sound through the ear.

Activation and use: Devices typically offer a T (telecoil) or MT (microphone plus telecoil) program. In T mode, only the telecoil signal is used; MT combines it with microphone input. The wearer generally needs to be within a few meters of the loop for best performance and to have the loop within the device’s field range.

Applications and advantages: Looped systems are common in theatres, churches, airports, banks, and conference rooms. Telecoils provide a clearer signal with less background noise and feedback, and can improve listening comfort in reverberant spaces.

Limitations and considerations: Effectiveness depends on proper loop installation, device compatibility, and distance from the loop. Interference from metal structures or other magnets can reduce performance. Not all venues have loops, and not all hearing devices include telecoils. Testing is recommended when visiting new sites.

History: Telecoils were introduced in mid-20th-century hearing aids and became widely used with the expansion of induction loop networks in public spaces during the late 20th century.