A noise-cancelling earplug assembly is provided, having an ear piece for insertion into the ear canal and a housing removably attached to the ear piece. A hollow core is defined in the housing to receive a sound-selective sound barrier that contains at least one sound filtering element to attenuate sounds reaching the ear drum. An end cap is provided and is attachable to the housing to enclose the sound-selective sound barrier inside the housing. The sound selective sound barrier can be removed from the housing of the earplug and replaced with a different sound selective sound barrier with different sound attenuation characteristics.
