What Is The Haas Effect In Audio Production? (+Tips & Tricks)

  • Learn what the Haas effect is.
  • Learn how to utilize the Haas effect in your music production.
  • Tips and techniques to create aural interest in your mixes.

What Is The Haas Effect?

The Haas effect is a psychoacoustical phenomenon discovered by Helmut Haas in 1949.

The origins of its discovery lie with Hans Wallach who described it as the ‘precedence effect’ stating simply that if two identical sounds are heard in close succession then they will be perceived as a single sound.

Haas expanded on this and discovered that in fact any identical sounds presented within approximately 40 milliseconds of each other will still be heard as one by the human ear. 

We won’t bog you down with the finer points of the physics of the Haas effect, but this phenomenon is a very useful tool to utilize when it comes to audio production. 

The Haas Effect in Mixing

The Haas effect is something that you almost certainly will have experienced when listening to any modern music in stereo.

A very common approach to thickening up the sound of a guitar riff is to double-track when recording (i.e. record one take of the riff, then record another onto a different track but playing the same thing).

Doing this can result in a ‘chorusy’ effect of the guitars when center-panned.

This is due to the fact that the riffs (no matter how accurate the player) will in certain areas be out of time, or phase, with one another.

However hard panning the takes, one left and one right, will open up the stereo image and create a much wider sound which you will often hear in rock music and eliminate the chorus effect.

It’s at this point that the Haas effect becomes most effective – our ears are hearing what appears to be a single riff but the timbre and tone become more powerful and fuller to the ear as the one sound we are hearing is actually made up of two guitars. 

In fact, it’s not uncommon for several guitars to be layered to enhance this effect, often using different pickup configurations, amps and pedals.

Have a listen to our examples below.

The first is a double-tracked, distorted riff center-panned, whilst the second is the same two takes hard-panned left and right. Notice the difference in tone and power in the second example.

It’s worth noting that this using this technique isn’t ESSENTIAL to getting a great distorted guitar sound.

A guitar solo traditionally would be single-tracked. This is because solos would typically incorporate higher frequency notes which stand out more in the mix. By single-tracking and center panning the solo is brought more to the forefront of the mix. A double-tracked solo can easily illustrate inaccuracies in each take depending on the complexity of the passage.

This isn’t a black and white rule of course, you may find a double-tracked solo or a single tracked riff actually works just fine, but it’s worth keeping the Haas effect in mind as it can add extra depth and power to your guitar tracks.

Sample Delay For Cleaner Haas Effect

Another way of thickening up your sound is to use a sample delay, rather than double-tracking.

As we’ve mentioned, double-tracking guitars is a really simple way of thickening up your tone, common in rock, metal and punk.

The great thing about recording with distortion is that small mistakes or inaccuracies often aren’t noticeable as they are disguised by the distortion itself.

That’s not to say that rock guitarists aren’t great players, in fact most of them are highly skilled and well-rehearsed players but heavier distortion by nature may cover up small inconsistencies between tracks such as string squeaks or timing between chord changes.

But what about if you’re recording clean guitars?

Even small differences in your takes such as a difference in pick attack can be much more prominent and difficult to edit out.

A much easier way to create the Haas effect in this scenario is to record a single take to pan left, then simply duplicate the take and pan right or send your existing track to an auxiliary channel and pan right.

Insert a sample delay onto the duplicated track and increase the delay by any amount up to around 30-40 milliseconds. 

The effect simply delays the riff slightly, creating the Haas effect. This is different to a normal delay plugin which would keep the original in place and playback a repeat after a certain amount of time.

In the example below, we have a clean track panned left but also being sent to a bus track panned right.

Listen as the sound starts to thicken up as the delay time increases.

You’ll also notice as the delay crosses the 30-40 millisecond threshold that your ears start to perceive the riff as two separate sound sources.

The great thing about using this method is you don’t have to spend unnecessary time double-tracking the perfect take or editing out inaccuracies in each track.

The sample delay will cause a thicker sound without becoming too aggressive or unnatural sounding.

Haas Effect (Not Just for Guitars)

OK so we’ve talked a lot about guitars in this article. But the Haas effect can be used on just about anything to enhance your stereo image and create greater depth to your mixes.

An effective way to add even more character is to have two tracks playing simultaneously but use effects such as EQ or light Modulation to change the timbre of one of them.

Try panning a synth track left and right with a short sample delay but making some slight EQ changes to one of them.

It’s best to be subtle, your ears will pick up any unnatural sound (if you use a high pass filter to cut all the way up to the mid-range for example), so try a slight boost or cut here and there – your ears will still perceive this as one track, but the tonal differences will create a much more characterful stereo image. 

The Haas effect is a really useful tool when it comes to enhancing your mixes.

Think about when to use it and when NOT to use it.

Opening up from a single center panned instrument track in a verse to a double-tracked hard-panned chorus is a great way to add impact, dynamics and contrast to your mix without having to simply make things louder or quieter.

Have you found any creative ways of using the Haas effect in your mixes? Link us below!