It’s true: You do not need to buy more speakers or re-arrange your workspace to get started with immersive audio. Dolby Atmos is scalable, from complex surround systems down to a two-channel immersive format that works exclusively with headphones or earbuds. Because many people listen to music over headphones, and mixing on headphones is doable, this isn’t a huge limitation The only gear you need to get started with Atmos immersive mixing is headphones and a DAW with Atmos (e.g., Pro Tools Studio/Ultimate, Studio One, Cubase/Nuendo, Logic, etc.).

Doing movie-level Atmos mixes is a deep subject with a major learning curve. This post is about how to get started with immersive audio mixing as simply and easily as possible—not how to mix the next blockbuster movie. For a deeper dive, Dolby has Atmos courses you can take to supplement your DAW’s documentation.

Why Immersive Audio is Possible with Two Channels

Traditional surround directs audio to specific speakers. Atmos isn’t audio, like a WAV file. Instead, it uses metadata to place mono or stereo sounds in a virtual 3D world. This is why it’s scalable. Atmos is a traffic director for metadata. The traffic it directs is the audio.

Although it’s counterintuitive that headphones can deliver immersive audio, in an acoustic space the sounds that reach your ears have varying levels, frequency responses, and delay times depending on whether they arrive from the front, sides, above, or behind. Binaural recording captures these aural cues that provide sound localization. Although it uses two channels, it’s not the same as standard stereo.

The Atmos process simulates a real-world space. When you mix, you can create the illusion of sounds being around you, not just in front of you. Although headphones can’t deliver an experience like sitting in a home theater and being surrounded by multiple speakers, headphones can deliver an experience that’s beyond traditional stereo. Check out Dolby’s short YouTube demo while listening on headphones.

Binaural audio’s use of headphones has a bonus advantage. Because listeners listen over headphones, mixes will likely translate better than listening over speakers.

Mixing in Atmos for Immersive Audio

Compared to stereo, binaural mixing has four major differences:

• Atmos projects require a 48/96 kHz sample rate and 512 sample (or more) buffer. This buffer size creates an objectionable delay for recording instruments in real time. So, I track with stereo projects for low latency, and switch to Atmos for mixdown.
• Binaural mixing can use mono, stereo, or multichannel tracks. For example, with a 5.1 surround-compatible track, a mixer channel’s level meter will show the levels of all six audio streams.
• The surround panners for immersive audio offer way more capabilities than traditional stereo pan-pot functionality.
• The last link in the immersive audio signal chain, the Renderer module, converts audio created in the format used for mixing to the target delivery format (e.g., binaural, stereo, or surround).

Atmos was developed for movies, so it incorporates two different audio elements:

• A surround mix (the Bed). This is based on conventional mixing techniques, with defined channel specs—like 2.0 (stereo), 5.1, or 7.1 surround. When creating the bed, you mix on headphones in emulated surround.
• Objects are typically mono or stereo audio. You can place them anywhere in the 3D Atmos space. These independent audio streams can float and move in space. They’re ideal for movie sound effects, like a car speeding by.

The process itself is simple. You mix in surround, monitor the mix as binaural audio in headphones, and then render the audio to a two-channel binaural audio file.

Setting Up for Surround for Immersive Audio

Atmos is somewhat like MIDI is that not all Atmos implementations include the entire feature set, but there are far more similarities than differences. Once you match Atmos’s sample rate and buffer requirements for your audio interface, there will be an initial setup procedure. This typically involves inserting the Renderer in your projects, choosing the bed format, and deciding whether you want to use objects. It doesn’t matter what bed format you choose—5.1, 7.2.1, whatever—because the Renderer will eventually direct your bed mix and objects to binaural. (However, note that the height parameter will be of limited usefulness with most headphones.)

You also need to make the output connections. Disconnect your usual stereo output, and assign the Renderer’s output to your audio interface’s standard stereo output bus (fig. 1). The Renderer will render to binaural over the two channels (or stereo if you choose that as the Renderer’s mode).

Binaural Mixing  with Surround Panning for Immersive Audio

Surround panning is the main difference with stereo mixing. It places sound around you by supplementing stereo’s left and right channels with more positions (fig. 2). For example, a 5.1 channel system adds speakers for the center, left rear, right rear, and a subwoofer. (Center is intended for dialog and the subwoofer is mostly for effects, so they aren’t commonly used for binaural mixes. With music, the left and right channels create a phantom center, and most instruments don’t generate ultra-low frequencies.)

Headphones don’t give the “bathed in sound” effect of surround speakers, but compared to stereo, surround panning gives more parameters for positioning the audio. All of this may be hard to absorb at first, but don’t worry about it. Just dive in—you’ll hear how these controls affect the sound. It’s revelatory to place sounds in a sound field instead of settling for the usual two-dimensional left/right line of standard panning.

After doing your mix, set your Render parameters, and render to Binaural (fig. 3)

 

How Listeners React to Immersive Audio

When listeners initially compare binaural mixes with conventional stereo mixes, they often don’t notice much of a difference because the instrumentation and the song itself haven’t changed. The bass is still the bass, the singer is the same singer, the arrangement is the same, and so on. What does change is the sound. There’s an analogy with pitch correction. Initially, you don’t notice it because you’re listening to the vocal. But then your ears start to hear pitch-correction artifacts. Eventually, you can’t unhear pitch correction. With Atmos, if you listen to Atmos mixes for a while, your ears get used to the expanded soundstage. Returning to stereo sounds oddly “flat.”

Although Atmos hasn’t conquered consumer audio, it’s not over…yet. Remember that stereo and mono vinyl records co-existed for a decade before the transition to stereo was complete. The transition from vinyl to CD took about as long. Currently, few streaming services let users upload immersive multichannel file formats. YouTube won’t let you upload a 5.1 multichannel file, but it can play back Atmos files that have been rendered as two-channel binaural audio. As long as people listen on headphones or earbuds, the music will have an immersive quality. I sometimes  upload both  binaural and stereo song versions, so listeners can choose whether they want to listen to the Atmos binaural mix on headphones, or a conventional stereo mix on speakers or headphones.

But the bottom line is that doing binaural mixes is fun—so give it a shot!

Craig Anderton is a music industry legend—from his teenage touring days, to production and mastering projects for artists from classical to hardcore, to his current work in disrupting the publishing industry.  Recent e-books include Innovative Techniques for Pro Tools, The Huge Book of Studio One Tips & Tricks, The Big Book of Cubase Tips & Tricks, and How to Record and Mix Great Guitar Tracks. Visit his free educational website at craiganderton.org, and hear Craig’s latest music releases on his YouTube channel.

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