A hearing aid includes a shaped body that is adapted to an individual auditory canal. The bus state controller includes control registers such as wait controllers, and parallelly controls the interfaces of various semiconductor memories and PC cards. The test packet contains an additional field that is subject to being modified as the test packet traverses the network. Thus, the packing system of the present invention provides a simplified method to load and monitor a barrier in the stuffing box of the valve to slightly higher pressure than processed fluid pressure.