The Linkx IRA 89 is a complete sound field system designed for installation is class rooms. Each sound-field system kit consists of an infrared wireless microphone worn by the teacher, which is transmitted via loudspeakers placed strategically around the room. The system increases the teacher's voice level and also decreases the distance from each child to the teacher's voice, which removes the problems associated with reverberation.
In an experiment conducted by NAL, the use of sound-field systems resulted in a 41 per cent increase in the rate of attainment of educational indicators during the terms the systems were installed. This was averaged across all children in the classes and across reading, writing and numeracy skills and occurred despite most of the children having no problems with their hearing.