How To Use HAAS Effect In Mixing Music - The Ultimate Guide

HAAS Effect is widely used by professional mixing engineers to create space and stereo width in tracks. It is fairly easy and simple to implement in your mixes. Yet, most beginner producers and audio engineers still find it confusing. 

In this article, I have tried to simplify the HAAS effect and how to use HAAS effect in audio mixing.

What Is HAAS Effect?

HAAS Effect occurs when two similar sounds have a very short delay between them(less than 40ms). Due to this short delay between the sounds, the human mind perceives the sounds to be spread out and wide. HAAS effect can be used while mixing to create a sense of space and width, creating a wider stereo image.

Dr Helmut HAAS developed the HAAS Effect in 1949, and it's a kind of psychoacoustic phenomenon. This law, also known as the "precedence effect," asserts that if a sound occurs within 40-50 milliseconds of another sound (below the threshold of human echo perception), the two sounds are perceived as a single sound.

In fact, how we use sound to establish a spatial location is heavily influenced by this impact. The initial noise that we hear determines our spatial location. Because the delay between the two noises is so brief in this scenario, the first sound becomes the dominant sound and takes precedence regardless of where the second sound originates.

In essence, we establish the source of a sound by determining which sound arrives first in our listening position. Even if these sounds are not heard individually, the short delay or later reflections and noises help us experience spaciousness and depth.

How To Create HAAS Effect In Mixing Music

To create HAAS Effect while mixing music, follow the steps mentioned below:

1. Duplicate a Mono Channel to a new channel.
2. Hardpan one of the channel to the left and the other one to the right.
3. Delay any one channel by 10-50ms.
4. Listen to the width and taste. Make delay changes accordingly.
5. Delays less than 10ms will create a phasing effect which might sound odd on long sustaining sounds(like a pad) but can be used on short sustaining sounds(like a snare drum).

Pro Tip: - The more delay you use, the more you improve the directionality of your sound, albeit this only works up to a limit. If you go past 50ms seconds, the sounds will be perceived as two different delayed sounds.

Use Of HAAS Effect In Mixing

There are a multitude of ways to use the HAAS effect in your mixes to help you get unique outcomes. The HAAS effect can help you eliminate directional masking in your mixes, improve overall stereo image, and thicken up your mix transients with early reflections on your reverb plugin.

HAAS effect is best suited to the following sound types: - 

1. Guitar Sounds - Both electric and acoustic.
2. Synth Sounds - Arpegiatted synths and SAW synths work great.
3. PADs - A longer delay around 40-50ms adds space to the pads
4. Snares - Short delays create an impact on snare sound.
5. Claps - Cleans up centre space when using claps.

Suggested Delay Time To Create HAAS Effect

Is HAAS Effect Mono Compatible?

The simple answer is no. When heard in stereo, the HAAS effect can be rather striking, but when mixed to mono, the tone and loudness will most likely change—if the sounds don't totally disappear due to phase cancellation. Of course, outside of the 5ms-35ms range, you might raise the delay. However, this defeats the purpose of using the effect in the first place, as you want to hear a single sound rather than multiple echoes. 

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