Abstract: A short range communication or signalling system uses induction field FM or PCM capture effect properties to transfer information to receivers located outside the aerial configuration of the transmitter. When used as a deaf aid, the receiver is equipped with a conventional hearing aid for use when the transmitter is silent. Switching of the transmitter and receiver from one mode to another is achieved manually or using a VOX system. Adjustable sensors of field strength may be provided in the receiver (a) to inhibit transmission when a nearby transmitter is already operating and (b) to reduce the effective range of the receiver.