Assistive Listening Devices

Assistive Listening Devices (ALDs) are devices used in addition to hearing aids and cochlear implants to make more sounds accessible to people with hearing impairment.

Specifically, hearing aids and cochlear implants are traditionally designed to enhance conversational speech, in one-on-one situations and in relatively quiet situations. However, while listening in the presence of significant background noise, or at a distance, or in special circumstances such as listening to a television playing from across the room, or while trying to use a telephone or listening to the radio, or at a lecture in a large hall, additional listening support is useful.

FM Systems

FM systems are very useful and very popular in educational settings. FM systems are micro- radio transmission systems (hence the name “FM”) that maximize the speaker’s voice. FM is traditional known for its use in the classroom. The teacher speaks into a tiny and portable microphone (usually clipped onto his/her collar) and the sound is delivered wirelessly into the student’s hearing aids using FM signals—thus, avoiding the introduction of background noise, reverb/echo, and while maintaining an excellent signal-to-noise ratio.

FM is also very useful for adults in many listening situations. Systems are also available for use with adults where the spouse, loved one, or speaker at a meeting would wear a microphone, much like the teacher. These systems are easily portable, and have been known to assist users in the car or at a noisy restaurant.

Sound Field Systems

Another popular listening system designed for classrooms are sound field systems. While employing sound field systems, the teacher wears a small, wireless, microphone and the sound signal is sent to strategically placed speakers located across the classroom to enhance the speech signal. Sound field systems are not only beneficial for students with hearing loss, but many studies have shown that all students in the classroom benefit when sound field systems are used to improve classroom acoustics.

T-Coils and Loop Systems

Indeed, most people with hearing loss depend on or benefit from some kind of ALD to help them develop or maintain a comfortable level of independence in their daily lives. From infra-red TV headsets to closed-captions (CC) used while watching TV, to amplified telephones, people with hearing loss use a multitude of ALDs to remain connected to their world. Other popular ALD systems include telecoils (also called T-Coils, available in many hearing aids for more than 50 years) and loop systems. Loop Systems transmit electromagnetic signals into a “looped area” (such as a living room or an auditorium) allowing the hearing aid wearer to perceive the sound signal through the telecoil switch on t-coil supplied hearing aids.