As a result of its construction, every loudspeaker has a certain inertia. In other words, there is always a slight delay between the application of the electrical signal and the creation of the sound. In addition, the driving voice coil is usually positioned slightly behind the baffle. As a result, the sound has to travel this additional distance, which causes a further delay. The time delay can be converted into additional virtual travel by applying the velocity of sound and this gives us the apparent distance by which the source of the sound is shifted behind the baffle. The result of the shift is described as the acoustic source. This is a necessary factor when simulating and observing the relation between the phases of several drivers at the same time.