Hearing aid for classroom use - has ninety degree phase shifter connected by twin channel amplifier to overlapping rectangular induction coils

摘要

The sound amplifying system for the hard of hearing is designed for use in a classroom where there are different zones with sounds at different levels. The device used can also be used with a radio or T.V. receiver. It consists of a 90 degree phase shifting section connected to a double channel amplifier and two induction coils. After the two phase shifted signals have been amplified, the two signals are passed to the two coils. These are rectangular in shape, with their longer sides parallel, having a specified proportion. One coil overlaps the other, the overlap being one third of the overall length of the two overlapping rectangular loops.