Assistive Listening Devices (also called Assistive Technology) can be used with or instead of hearing aids. Examples of assistive listening devices include FM systems, soundfield systems, induction loops, telephone devices, television amplifiers etc.
The two most used assistive listening devices for microtia & atresia patients are FM systems and soundfield systems, and will be discussed here in more detail. These devices are particularly useful for classroom settings. Unfortunately, most school classrooms are not ideal listening environments. The distance the student is from the teacher, background noise and reverberation all make it more difficult for the hearing impaird child to hear in the classroom.
FM (Frequency Modulated) Systems are used to transmit sound from one person to another. They can help overcome the effects of noise, reverberation and distance, and are used in classrooms to help students overcome poor listening conditions. FM systems improve the quality of the sound that students receive.
There are two components to an FM system – a microphone & transmitter worn by the speaker, and a receiver worn by the person with a hearing impairment. The FM system transmits sound from the speakers microphone to the listener’s receiver via radio waves. The receiver can be attached to the child’s hearing aid (if applicable) or used with earphones.
Australian Hearing provides various types of FM systems. Some are completely funded, while others can be purchased by parents.
Soundfield systems are a useful assistive listening device often used in classrooms of children with a hearing loss. Soundfield systems help overcome the problems of poor classroom acoustics, hearing the teacher’s voice above background noise and hearing the teacher when they are not positioned directly in front of or close to the student.
A soundfield system comprises of a wireless microphone (worn by the teacher), sensors and speakers (mounted on the classroom walls). The microphone picks up the teachers voice and sends a signal to the main sensor (base unit), where the sound is made clearer, amplified and sent to the speakers. The speakers are mounted around the room to make sure the teacher’s voice is heard in all areas of the classroom. Sound levels decline dramatically over distance, so once the soundfield system is installed, the teacher can move around the room and their voice will still be distributed evenly. Therefore, every child will be able to hear the teachers voice no matter where they are sitting or where the teacher is.
Children with all types of hearing loss can benefit from a soundfield system, however these devices are particularly beneficial for children with mild or unilateral losses. In actual fact, a soundfield system benefits all children in the classroom – not only those with a hearing impairment.
Soundfield systems are not available through Australian Hearing, so schools have to fund these. Some parents have chosen to purchase soundfiled systems for their child’s classroom if school funding is not available. The Lions Hearing Dog program provides a limited number of grants each year to fund soundfiled systems in classrooms for hearing impaired children.