1. In a communication system comprising a primary circuit for transmitting an audio signal from a speaker microphone to an audience through transmitter means, first booth means, means connecting the speaker microphone signal to the first booth means where the audio signal of the speaker is translated into a medium language, second booth means, means connecting the translated medium language to the second booth means where the medium language is translated into final languages, a plurality of secondary circuits connected to the first and second booth means, each circuit having transmitter means for transmitting to the audience an audio signal exclusively used for a translated language, a first diode matrix having a plurality of transverse lines connected to a power source via holding-releasing circuit means and switch means, and obverse lines connected to interpretation display lamps in the first and second booth means, each of the obverse lines being connected to a first selector with one selector associated with each of the booth means and its respective secondary circuit, diode pins arranged to connect and disconnect selected transverse lines with selected obverse lines for alerting translators in the first and second booth means and for energizing certain first selectors so as to transmit translated languages to the audience through certain secondary circuits, the first selectors serving to connect and disconnect between booth amplifiers, one associated with each booth means, and second selectors, the second selectors serving to connect and disconnect between the first selectors and the transmitter means of the secondary circuits, the improvement comprising a second diode matrix having second transverse lines connected to the power source via a second holding-releasing circuit and second switch means, and second obverse lines each connected to one of the obverse lines of the first diode matrix, second diode pins arranged to connect and disconnect the second transverse lines with selected second obverse lines so that the interpretation display lamps in one of the first booth means and in each of the second booth means are energized together with the secondary circuits associated with these booth means whereby even when an additional language is spoken other than the specified languages translation of the additional language is accomplished without interrupting translation of the specified languages.