Haas Effect Panning

History

A smart guy named Helmut Haas discovered a bunch of cool things about the way our human brains decode the sounds we hear to determine the direction of where those sounds originate.

Back in 1949, Mr. Haas found that early reflections of sounds help our brains decipher where the sounds came from. We can tell a noise came from the left not simply because we hear it in our left ear, but also because the sound bounces off a wall to our right and hits our right ear a very short time after it hit our left ear. Almost instantaneously, the brain detects the short time between the two signals and tells us, “Hey, that sound you just heard came from your left. Better turn your head to see what it was!” This happens so quickly that we don’t really even think about it. We just “know” it came from the left.

Haas also recognized that early reflections are basically copies of the initial sound that are delayed slightly. He started messing with people’s heads. He pointed speakers at them and firing sounds with very short delay differences. Then he asked the test subjects which direction the sound seemed to come from.

His conclusion: Not only is it fun to play with sounds, but also 40 ms (milliseconds) is some kind of magic point for our brains. If an echo is more than 40 ms after the initial sound, then we hear the sounds as separate instances. But if the delays happen within 40 ms or less of each other, then we perceive them together as merely directionality cues of a single sound.

For example, if a sound hits our right ear and the same sound hits our left ear 0.3 ms later, we don’t hear two sounds, we only hear one sound coming from approximately our 1 o’clock position.

And so the Haas effect was named after him.

Panning

Engineers have implemented the Haas effect as an alternative to panning. Most of the time panning works just fine, but it does have limits.

Sometimes panning leaves the location of the audio feeling indeterminate, smeared, mono, or one dimensional. This is why a lot of engineers skip the pan knob altogether and mix LCR.

To effectively localize a track in a stereo field using the Haas effect, engineers have to do a couple things. They duplicate the track, pan the two tracks hard left and right, and then apply a delay to only one of the sides. The delay is applied to the side opposite of the side from which the sound is intended to perceived as originating.

Typical delay times for this technique are increments of 0.1 ms from 0.1 to 0.7 ms. This yields linear movement across the stereo field. You can think of it like this chart shows.

Example: Want the sound to come from 9 o’clock on the left? Delay the right side by about 0.4 or 0.5 ms.

Download

After researching the Haas Effect, I decided I wanted to try it out in a mix. Since the settings must be very exact, setting it up correctly can be a bit confusing. Presets to the rescue!

I made these presets for the stock Digidesign Mod Delay II plug-in. These presets only work for this specific plug-in and Pro Tools. If there’s interest, maybe I’ll make more presets for other DAWs in the future.

Installation

Download this ZIP file, unzip it, and drop the folder and included presets in the Mod Delay II folder in the Plug-in Settings folder. On a Mac it’s probably located at Library / Application Support / Digidesign / Plug-In Settings / Mod Delay II, but may be in a different location on your system.

Setting up the tracks

Insert an instance of the Mod Delay II (mono/stereo) plug-in on the mono track you want to Haas-ify. Select the preset you want. No need to duplicate tracks. Bingo.

Haas Effect Panning

Digging Deeper

Understanding how to use the Haas effect properly means you need to understand and pay attention to things like stereo-to-mono compatibility and comb filtering, as well as other stereo field mixing techniques. As with all effects, have fun but be careful not to over do it. Experiment and do your homework. Then let me know if you find learn or discover anything cool. Here’s a cool video that got me thinking about the Haas effect. This video no longer available.