Also known as the Precedence Effect. The human ears do not rely solely on different loudnesses to determine the direction from which a sound is coming; they also use timing. It is often the case that timing trumps loudness. If the same sound arrives from two different directions, the ear will tend to identify the direction of the source as that of the first sound to arrive, even if the other sound, arriving a few milliseconds later, is significantly louder. This is why it is important to properly adjust the time alignment of surround speaker systems. This effect is also made use of in high quality sound reinforcement systems in concert halls, since by delaying the sound coming from speakers near the back of the hall, it can be made to sound as though the high volume coming from those reinforcing speakers is actually coming from the front of the hall.