Patent ID: 7401680

Claim:
A hearing protection earplug comprising a shell to be worn at least in part in a user's ear canal, said shell being adapted to provide for a mechanical acoustic attenuation of at least 10 dB averaged over an audible frequency range when worn by said user, an active unit comprising at least one of an acoustic output transducer and a microphone and means for detachably connecting said active unit to said shell, wherein said shell comprises a sound passage extending between an outer opening of said shell and an inner sound output opening at a distal end of said shell and comprising valve means which are moveable, upon connecting said active unit to said shell, from a closed position in which said valve means acoustically close said sound passage into an open position in which said valve means acoustically open said sound passage, said valve means being biased towards said closed position in order to acoustically close said sound passage when said active unit is removed from said shell, and wherein said at least one of an output transducer and a microphone is acoustically connected to said sound output opening via said sound passage when said active unit is connected to said shell.