Technical possibilities in the school situation for the education of hearing-impaired children.

For hearing-impaired children, the main problem in the classroom is the signal-to-noise ratio. To improve the signal-to-noise ratio, several class systems have been developed, three of which have been investigated in this study. The systems are shown to be equivalent in a situation without a channel for pupil response. Application of such pupil response channels will decrease the improvement in signal-to-noise ratio brought about by the class system. It is argued that the choice among several combinations of class system and pupil response channel is governed by the primary goal of education and how this goal is to be achieved.