A method of managing the number of base station engaged in soft hand-off in a mobile communication system. A speaker box of a speaker device includes a baffle, four intermediate plates, and a rear plate. Electronic components are fabricated on the same substrate material, allowing sensors and controlling circuitry to be incorporated in the same device. The elongated channel has or forms a window for transmitting light emitted by the light emitter into the interior of the access device. The third target module is for forming a quasi-parallel third patterned light beam being shed on the optical device. The adaptive chord is then extracted to coarsen the FEM.