Vox Studio has the capability to re-center a sound signal around the zero baseline if, for whatever reason, a DC offset or a very-low-frequency interference has been added to the original sound signal.
Some low-cost sound cards can introduce very significant and disturbing DC offsets. You don't necessarily hear the offset, but it may cause a loud click at the beginning or end of a file. Centering removes the signal's DC bias, and is therefore also useful if the signal has to be amplified considerably.