Abstract: Each of a pair of ear pads is provided with an electrically-operated earphone. The earphones are connected to each other by a circuit having a cord for connecting the earphones to an external audio-signal source. The circuit includes a pair of Zener diodes connected in back-to-back or opposed parallel relation to each other, and in parallel to the earphones so that if an incoming AC audio signal exceeds a predetermined value one of the diodes will fire to short the input signal, thus limiting the output (in decibels) of the earphones. A field-effect transistor is connected in series with the earphones to limit the current load thereto.