Assistive Listening Devices

Assistive listening devices (ALDs) are important complementary devices to your hearing aid. Oftentimes, those with hearing loss find it difficult to attend large events, such as a conference, as the background noise can be overpowering. ALDs are able to provide additional amplification by delivering clear sound directly into the hearing aid.

The basis of all ALDs is a telecoil. This telecoil, also called a t-coil, is a small wire that acts as a receiver inside the hearing aid. Most modern-day hearing aids come t-coil enabled. An induction loop, infrared and FM are the three most common systems.

An induction loop utilizes electromagnetic energy to transmit sound. This system has four parts: a sound source, amplifier, thin wire loop that goes around the perimeter of the room and a receiver that is worn in the ear (the t-coil enabled hearing aid). Amplified sound travels through the wire loop until it is picked up by the t-coil. This type of system is ideal for conference centers.

An FM system uses radio waves to transmit sound. A small microphone must be worn by the speaker; it is either hung around the neck or clipped onto their shirt. The microphone is connected to a small transmitter. Speech is then broadcast from the transmitter over FM waves and picked up by the t-coil enabled hearing aid. This system is used primarily in classrooms.

An infrared system is able to transmit sound via infrared light. The light is picked up by the t-coil enabled hearing aid and converted back into sound. Since light cannot pass through walls, unlike radio waves and electromagnetic energy, this system is ideal for situations where sensitive information is discussed, such as a courtroom.