An acoustically permeative intracanal cap is adapted to be worn semi-permanently deep in the ear canal for shielding a hearing device positioned deeper within the ear canal against moisture and debris infiltration. The intracanal cap conforms circumferentially to the walls of the ear canal for occlusion thereof, and comprises a porous membrane with pores sized to prevent water and solid debris from entering the ear canal while allowing air-conducted sounds to freely reach the microphone of the shielded hearing device. The intracanal cap may be entirely separate from the hearing device for independent insertion and removal, or attached to a lateral section of the hearing device for concurrent insertion and removal therewith into and from the ear canal.