Also called "T-coil mode," it is an optional wireless mode in phones that can be selected for wearers of telecoil-based hearing aids. A telecoil is a tiny wire-wrapped rod (induction coil) that serves as an antenna to pick up electromagnetic energy and convert it to electricity. Phones rated T3 or T4 work best with telecoil hearing aids.
No More Background Noise
When both the phone is transmitting and the hearing aid is receiving in telecoil mode, the local background noise is greatly reduced. Telecoil systems are also used in public venues where an "audio induction loop" ("hearing loop") is a ring of copper wire or tape that encircles a room, counter, drive-through or chair cushion. The loop is connected to the public address system and transmits audio signals to telecoil users.
Users can also wear a "neck loop," which is a wire worn around the neck that plugs into an iPod, CD player, TV or other sound source using the appropriate cable connector. The neck loop transmits the audio signals to the telecoil in the hearing aid. Bluetooth neck loops are gateways that provide audio conversion from any Bluetooth-enabled smartphone, tablet, laptop or iPod to the hearing aid. See NFMI
Ditch the Background Noise
When hearing-impaired users see this sign, they can switch their hearing aids to T-coil mode and pick up announcements directly without background noise. (Image courtesy of HearingLoop.org, www.hearingloop.org)