In an embodiment of the invention, an apparatus and method for storage space management performs the steps including: activating a logical volume group; reading pattern-based mapping information from physical volumes in the logical volume group; and using the pattern-based mapping information to determine a target physical extent in at least one of the physical volumes for a received request. In one embodiment, two earphones are connected by two corresponding wires, and two microphone arrays, respectively connected to the two wires, are mechanically and electronically configurable in a plurality of use modes to generate outgoing audio signals for processing by the signal processor. The frequency divider inputs an output signal and a reference signal, divides the output signal, and outputs a feedback signal, and also outputs a select signal, a trimming signal, and a limit signal from the output signal.