ELECTRONIC EXCHANGE HAVING A CONFERENCE TELEPHONE COMMUNICATION FUNCTION AND CONFERENCE TELEPHONE COMMUNICATION METHOD

摘要

An improved (N - 1) adding operation conferencetelephone communication method through an electronicexchange in which the telephone communication signals onspeakers in a time sharing multiplexed telephoniccommunication path are added, the telephone communicationsignal on any particular speaker himself is subtracted andthe resulting telephone communication signals aretransferred to the remaining respective speakers. Thelevels of the telephone communication signals aremonitored which are obtained as the result of the (N - 1)adding operation. When the telephone communicationsignals exceed a preset threshold level. they areselectively attenuated and transferred to the remainingrespective speakers. The selective attenuation of thetelephone communication signals which have exceeded thethreshold level is released a predetermined time afterconditions under which the threshold level is exceededhave disappeared to thereby prevent satisfactorily thedeterioration of the voice quality which would otherwisebe feared.