Terms & Technologies Defined

What is a T-Coil?

A T-coil or telecoil is an electromagnetic device inside many hearing aids that can pick up sounds directly from induction loop systems. The t-coil can also be used with FM and infrared systems when a special neck loop is worn. Transmitted sounds go directly from the speaker into the hearing aid switched to the T-coil mode. T-coils are also used with analog telephones which emit electromagnetic energy from their receivers. New technologies are being developed to allow T-coils to connect with digital telephones as well.

Audio Loop (Electromagnetic Energy)

An Audio (induction) loop is a wire loop (or thin loop pad) attached to an amplifier. It creates a magnetic field that broadcasts sound, in pure, undistorted form, directly to people who are within the loop and have a hearing aid containing a telecoil.

Frequency Modulation (FM Radio Waves)

FM means utilizing a radio signal frequencies (instead of amplitude) to transmit useful information. There are special frequency ranges that are assigned for use by assistive listening systems. Systems will use FM to transmit the signal representing sound from a transmitter to a receiver. Some behind-the-ear hearing systems use a propriety jack, and others use a "boot", which slips over the end of the aid and electrically connects the source to the aid through three tiny brass dots on the underside of the BTE.

Infrared (IR)

Infrared is a means of using light to transmit a signal over a distance. The light frequency used in Infrared is above the range of visible light in the "red" end of the light spectrum. It doesn't go through walls and isn't affected by radio or electromagnetic interference. It's only suitable for indoor applications and it requires a clear line of sight between the transmitter and receiver.

Blue Tooth

Bluetooth technology is a short-range wireless communication technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The key features of Bluetooth technology are robustness, low power and low cost. A fundamental Bluetooth wireless technology strength is the ability to simultaneously handle both data and voice transmissions. This enables users to enjoy a variety of innovative solutions such as hands-free headsets for voice calls, printing and fax capabilities, as well as the ability to synchronize PDA, laptop, and mobile phone applications.

Alerting and Signaling Devices

Any signaling or warning sound can be turned into either a visual or vibratory signal for the hearing impaired. For example, doorbells can be wired to flash a light and smoke alarms can activate powerful strobe lights. Alarm clocks can employ light or vibration to wake up a sleeper. Parents with severe hearing losses can be alerted to the sounds of their baby crying by a sound activated light or by a motion detector.