People with hearing loss have trouble hearing when they are at a distance from the person speaking, when it is noisy, and in public places.
For children, this can be a particularly serious problem because children need to hear clear loud speech all of their waking hours if they are going to succeed in developing the auditory brain and learn language optimally.
While hearing aids, cochlear implants, and bone-anchored devices are designed to provide improved auditory access, they provide optimal access only when the talker and listener are close and when there is no competing noise. When there is competing noise or when the talker and listener are more than a few feet apart, additional technology is needed.
Types of group listening systems
The goal of group listening systems (hearing loops, FM systems, and infra-red technology) is to increase the size of the “Listening Bubble”
for people with hearing loss. In other words, additional technology helps a person with hearing loss hear things that are out of the range of their hearing aids, or in situations when speech is affected, or to hear better in noise.
Several different listening systems are available to improve hearing in noise. FM systems are the most common systems used in schools because they provide good quality signals with a broad frequency response. In the US, FM systems are the most common group technology and, while the quality is excellent, they require additional equipment to couple to hearing aids.
Hearing loops are common in Europe but less so in the US, although the movement to increase loop technology is growing quickly. Infra-red systems can also provide assistance in group situations, but they are not commonly used.
How do hearing loops work?
Hearing loops transmit an audio signal using magnetic energy to the telecoil in a hearing aid or cochlear implant. The loop can be set up in any room by stringing looped wires around the room. They can be used in large places like theaters, auditoriums, churches and temples, or in smaller places like meeting rooms, taxis or the checkout counter at a supermarket.
A loop can also be used to aid in hearing TV. The user has to turn on the T-coil on their hearing aid, cochlear implant or BAHA. The audiologist needs to be sure that the T-coil is activated, and the user needs to know how to turn it on and off. The signal from the group amplification system will be transmitted through the loop to the T-coil on the personal listening system.
Telecoil vs Mic-telecoil position
If the hearing aid or cochlear implant is set to “T” only, the user will hear only sound going into the group microphone. She will not hear people sitting close by and will not hear her own voice. I am not excited about putting kids in a position where they cannot hear those around them. However, if the hearing aid or cochlear implant is set to the “M-T” position, the child should be able to hear from the microphone of his own device as well as from the group microphone. It means that parent, teacher and child can communicate while listening to a program.
Frequency response of hearing loops
Hearing loops are great devices and important contributions to improve listening. However, loop systems have some limitations. The telecoil of hearing aids do not have as wide a frequency response as the hearing aid or cochlear implant microphones. Telecoils have a reduced high-frequency response. That means that a child may not hear high frequency phonemes, missing sibilant, fricatives, pluralization, etc.
Hearing loops for kids
Hearing loops are great for theaters, movies, auditoriums, museums, etc., but they should not be used in classrooms and in other situations in which listening is critical for learning. High frequencies are critical and need to be maximized. So make use of hearing loops for many listening situations that will improve socialization and activities.However, loops are not a substitute for the kind of high quality listening that is required in school.
