An electrical connector consisting of a plug and receptacle separately fastened to each other by means of helical double ribs, grooves and lug-mounted locking ring wherein coupling occurs after the lugs have traveled over transverse bosses positioned in the grooves. The bosses force the ring to expand outwardly so that as the lugs seat in position, an audio signal is emitted. The bosses also prevent the locking ring from vibrating out of position.