Interference occurs when two (sound or other) waves meet and either reinforce each other or cancel each other out. This effect is of particular importance with multi-driver speaker cabinets. Within the crossover range of a frequency crossover or where several loudspeakers are being used within the same range of frequencies, the drivers will all contribute an equal amount to the sound dispersion. If the axes coincide, the waves complement each other and produce a larger one but at other angles they cancel each other out completely because of their different paths. One part of the sound will then arrive at its destination before another. This is called phase displacement. At 0° phase displacement, the waves reinforce each other and at 180° they cancel each other out. Any other combination is possible in between. The further the drivers are from each other, the stronger this undesirable effect is. However, the effect can be turned to good use as, for example with the D'Appolito arrangement.