(Also called Precedence Effect) Simply stated, a factor in human hearing in which we perceive the source of a sound by its timing rather than its sound level. In his research, Helmut Haas determined that the first sound waves to reach our ears help our brains determine where the sound is coming from, rather than its reflection or reproduction from another source. The reflection of the sound must be at least 10dB louder than the original source, or delayed by more than 30ms (where we can perceive it as an echo), before it affects our perception of the direction of the sound. This is what helps us distinguish the original sound source without being confused by reflections and reverberations off of nearby surfaces. Understanding the Haas effect is particularly useful in live audio settings, especially in large venues where loudspeakers are time-delayed to match the initial sound waves coming from the source.