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Touchless Telecoil

The Touchless Telecoil (patent pending), developed by Micro-Tech Hearing Instruments, is an amplified telephone coil that uses an automatic switch in place of the conventional hand-operated switch.

For many years telecoils in hearing aids have offered a solution to the problems of telephone use by the hard-of-hearing. Acoustically coupling a telephone to a hearing aid often creates feedback due to the proximity of the telephone receiver to the hearing aid microphone. By using an inductive pick-up in place of the acoustic (microphone) pick-up, the telecoil eliminates this problem.

While the conventional telecoil works well for people who can handle a small toggle switch, it presents a challenge to patients with compromised manual dexterity. For some, the switching creates a minor but annoying delay in answering the phone or in starting a meaningful conversation -- 'Hold on a minute, while I adjust my hearing aid.' -- while for others, it is difficult or impossible.

Two magnetic phenomena are essential to the operation of the Touchless Telecoil. All telecoils rely on an inductive (or varying electromagnetic) field of sufficient strength radiating, or 'leaking', from the telephone receiver. The Touchless Telecoil relies additionally on the permanent magnet that is part of every dynamic transducer, such as those in most telephones. The stationary magnetic field in the telephone receiver provides the stimulus to flip the internal automatic switch in the hearing aid from microphone input to telecoil input.

Because the performance specifications of telephones are not all the same, some dynamic receivers may not have a stationary magnetic field sufficiently powerful to trigger the Touchless Telecoil switch. In such cases a small disk-shaped magnet, provided by Micro-Tech, can be attached to the telephone receiver to ensure reliable switching performance.

Similar variability may exist in the inductive field strength and frequency response of telephone receivers. Micro-Tech has addressed this problem by dedicating a separate programmable memory to the Touchless Telecoil. The adjustable response parameters in this memory are set to optimize the response of the hearing aid for inductive coil input, with the result that the wearer usually does not need to adjust the hearing aid volume control when speaking on the phone. When the phone is moved away from the hearing aid, the switch returns to the alternate memory, optimized for microphone input.

The Touchless Telecoil is currently being built in Micro-Tech's premier programmable analog and digital instruments, the Nx2 and Dx3. The company is exploring its expansion to additional circuits in its hearing instrument line.

The Touchless Telecoil has been very well received by hearing aid wearers, who are enjoying easier telephone use. All they need to do is pick up the phone and start talking - no fumbling for a switch, no resetting of the volume control, no embarrassing delays before starting a conversation.

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