Creating a Wide and Immersive Mix: Advanced Stereo Imaging and Spatial Effects

The stereo format is pretty amazing. Because we have two ears and a whole host of processing power in our brains, two simple channels can do a lot to create a sense of immersive space and bring us into the music. In modern mixing, a lot of thought is put into space, including making mixes sound wider and deeper. So, let’s look at a few ways we can do just that.

Understanding Stereo Imaging

First, let’s get an overview of stereo imaging.

Stereo Field and Panorama

The stereo field refers to the perceived placement of sound sources across the stereo spectrum. By strategically panning audio sources, we create a sense of width, separation, and spatial positioning within the mix. In other words, when a sound is panned to the left or right, it gives the listener a sense of where the instrument or element is located in the stereo image.

Panning instruments to different positions helps establish a balanced mix, and that’s why stereo has survived the ages. Guitars can be panned slightly to the left and right, providing a sense of stereo spread, vocals are often centered to maintain clarity and focus, and so on.

Depth and Dimension

On the surface, stereo is two channels – left and right. But we don’t just have that single dimension to work with. Because of how psychoacoustics works, depth is also essential to stereo imaging.

To be clear, by depth, we mean the perceived distance of sound sources from the listener. For the most part, we achieve this with reverbs. More reverb loosely equates to elements sounding like they’re farther away – especially when the source isn’t separated from the verb. We can bring the source closer by using less reverb, but if we want the best of both worlds, we can use pre-delay or sidechain the reverb to the source so that it ducks when the source plays – these two techniques are common in modern vocal mixing, where we want to create depth while also bringing vocals forward.

Delay and modulation effects can also contribute to the perception of depth. Delays can simulate a sense of space, while modulation effects like chorus or flanger can add movement and dimension. With an understanding of depth in a stereo field, we can strategically position elements and create a rich and immersive listening experience. That’s level one. Next, let’s talk about some more advanced techniques for widening the stereo image and enhancing spatial effects.

Widening Techniques

So, we have stage one: left-to-right placement. We have stage two: perceived depth using traditional effects. Next, we have widening, which is newer stuff.

Mid-Side Processing

One powerful technique for widening a stereo image is mid-side processing. It lets you manipulate the perceived width of a mix by independently adjusting the level and spatial positioning of the mid (mono) and side (stereo) components of the audio signal. By boosting the side content and attenuating the mid content, you can create a wider stereo image.

Maybe the most straightforward approach here is mid-side EQ. By applying EQ adjustments to the mid and side channels separately, you can shape the frequency response and spatial positioning of the mix elements. For example, you can boost the high frequencies in the side channel to enhance the sense of width, while keeping the mid-channel more focused and centered. It’s also common to high pass the sides, which further focuses elements like kick and bass in the center, tightening the low end, which can give space, which makes things feel wider.

Another approach is to use dedicated stereo imaging plugins. These tools provide advanced control over the stereo field, allowing you to adjust the width, balance, and spatial placement of mix elements. Depending on the software, they might do this with proprietary stereo widening algorithms that manipulate the phase, time, and amplitude relationships between the left and right channels and/or simply employ mid-side processing. The job is approached in a variety of ways by different developers, so you may have to try a few to figure out which you prefer.

Other Stereo Widening Effects

Mid-side processing isn’t the only way to widen a stereo source. Chorus, for instance, can create a thicker and wider sound – albeit with some change. In case you never thought about it, chorus simply duplicates the original signal and adds slight variations in pitch and timing. Obviously, this change may be too much for an overall mix, but using a little chorus is a great way to widen individual tracks. You can also do this with ping-pong delay, certain reverbs, and automation.

Of course, while widening techniques can create a sense of spaciousness, it's important to exercise caution to avoid phase cancellation or an unnatural stereo image, which is why it’s often smart to try widening individual sources first, rather than just reaching for a widener on the mix buss. When you do go that way, use these techniques judiciously to be sure the mix remains balanced and coherent.

Going Beyond Wide and Deep

Nowadays, when you hear the word “spatial”, you’re likely to think of Dolby Atmos, so we’d be remiss not to mention it briefly. Even though Atmos isn’t technically a stereo format, it can be rendered in headphones using binaural audio technique, so it stands a good chance of getting more and more common.

In brief, Atmos creates a three-dimensional audio environment that immerses the listener in a lifelike and multidimensional soundstage. Originally designed for cinema and home theater systems, it’s been adapted for music production fairly recently. With Atmos, sound can move dynamically and fluidly around the listener, including overhead, resulting in a more enveloping audio experience, with more opportunity for creativity with depth and space.

It's usually implemented with multiple speakers, but its object-based methodology allows Atmos to be rendered using binaural audio, meaning you can create Atmos mixes intended for headphones. Normal stereo speaker systems, however, will usually fall short in rendering accurate Atmos mixes. So, good old fashion stereo technique is still necessary to create stereo mixes that translate.

Still, it will be interesting to see how Atmos advances, and how we may use it to go farther with depth, space, and immersive mixing.

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