Abstract: Earplug comprising a plug member for blocking a man's ear canal, said plug member comprising at least one acoustic channel for channeling incoming acoustic energy to said man's ear. According to the invention, a detector for detecting an acoustic energy level or for detecting a control signal that is indicative for an acoustic energy level to be received, an acoustic valve positioned in said channel, and a control unit that, in response to said detector, controls said valve so as to attenuate the acoustic energy channeled through said acoustic channel.