The Haas Effect in Stereo Listening

What is the Haas Effect?

The Haas Effect, or precedence effect, describes how the human brain localizes sound based on the first-arriving soundwave.

The effect is based on the time delay between the first sound and the second sound (ex. left speaker and right speaker). Three general ranges determine how we localize sound:

1) 0-5 ms: Fusion

• Sounds arriving within 0-5 milliseconds of each other are perceived as a single sound with no localization.

2) 5-35 ms: Localization and Stereo Imaging

• Between 5 and 35 milliseconds our brain registers the two sounds as one sound but will perceive it coming from the first arriving wave.
• Ex. The left speaker wave arrives 15ms before the right speaker wave. To our brain, this sound is coming from the left.

3) 35+ ms: Echoes

• More than 35 milliseconds of difference between sounds and our brain interprets each sound wave as a separate sound. This leads to echoes
  
  

Optimizing Speaker Placement and Room Reflections

Recording engineers will intentionally use these delays in mixes to enhance stereo width and depth. Uncontrolled room reflections and poor speaker placement will interfere with the intended stereo imaging.

Follow these additional guides for proper speaker placement and finding your first reflection point to ensure your stereo listening remains true to the original recording.