Let’s throw some Psychoacoustics in the mix: the Haas Effect (or Precedence Effect)

The field of psychoacoustics is a mine of creative ideas, that can help to  improve your mixes with a bit of understanding of your hearing system.

The Haas Effect, also known as Precedence effect, is a binaural psychoacoustic effect, described in Helmut Haas PhD Thesis back in 1949. So, we have been knowing about this for quite a while now. Basically it says that when two identical sounds reach our ears with a time difference between 10 and 35 milliseconds (which is very little) our ears will perceive the two sources as a single sound. And this happens even if the second sound is higher in level (up to 10dBs). Our ears will still perceive the first sound as the sound source, and the two sounds as a single, fused sound.

We can use the Haas Effect to add spacial precence, to thicken a sound, to shape the sound of vocals without the use of reverb or delays. You can try with a rhythm guitars: copy a single recorded track into an empty track and then delay that by about 30ms. Pan the two tracks left and right (to recreate a binaural environment) and adjust the levels. You will add depth to the guitars, while still keeping them upfront in the mix. The field of psychoacoustics is a mine of creative ideas. Each week we’ll cover a different topic, to see how you can improve your mixes with a bit of understanding of your hearing system.

The Haas Effect, also known as Precedence effect, is a binaural psychoacoustic effect, described in Helmut Haas PhD Thesis back in 1949. So, we have been knowing about this for quite a while now. Basically it says that when two identical sounds reach our ears with a time difference between 10 and 35 milliseconds (which is very little) our ears will perceive the two sources as a single sound. And this happens even if the second sound is higher in level (up to 10dBs). Our ears will still perceive the first sound as the sound source, and the two sounds as a single, fused sound.

We can use the Haas Effect to add spacial precence, to thicken a sound, to shape the sound of vocals without the use of reverb or delays. You can try with a rhythm guitars: copy a single recorded track into an empty track and then delay that by about 30ms. Pan the two tracks left and right (to recreate a binaural environment) and adjust the levels. You will add depth to the guitars, while still keeping them upfront in the mix.

Suggestion: don’t use it too extensively in the mix. Let’s say, on a couple of instruments will do. We don’t want to confuse our ears too much, do we?

Below I’ll list a couple of links that you may find interesting, to put theory into practice.

1 – A very short tutorial/example by Ryan Sullivan, Head Sound Engineer at Red Bull Studio in Cape Town , (here’s the link to the page) on how to effectively use the Haas Effect of hip hop vocals. Watch it even if you dont like hip hop, because it’s simple, to the point – definitely a trick to experiment.

2 – A short video demostrating the free Quick-Haas VST/AU Plugin by Venn Audio – visit Venn Audio Youtube channel at this link : using the sound of a pair of scissors 🙂 the video shows the change in the auditory perception of the stereo image by adjusting just a single knob.

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