PreSonus Blog

You don’t need a massive surround system with speakers wired all over your studio to create immersive audio. Whether you want surround or Dolby® Atmos mixes, Studio One Professional 6.5 delivers immersive sound over not just speakers, but the headphones you already have. Although it’s counterintuitive that headphones pressed up against your ears can deliver immersive audio, binaural audio makes it possible—here’s why.

Binaural recordings capture audio using a dummy human head with molded, lifelike ear canals. There are two mics, one for each ear. Whether sounds are reaching human ears or microphones in dummy ears, sounds coming from the sides or back have different levels, frequency responses, and delay times compared to those sounds reaching your ears from the front. Incorporating these differences in audio played back through headphones makes it sound like you’re hearing audio from front, sides, above, and behind you. In other words, listening to a binaural recording through headphones sounds like you’re hearing sound in a real-world space. Which brings us to…

Surround

Before headphones can reproduce the effect of hearing immersive audio, we need to create music in the studio that provides a feeling of space. One option is surround sound, which has been applied to movies for almost half a century.

Surround places sound all around you by supplementing stereo’s left and right channels with four more speakers: center channel for dialog, left rear, right rear, and a subwoofer for a movie’s bass requirements—explosions, earthquakes, and so on. When mixing music for surround, the center isn’t as important as it is for movies, because placing the same audio in the left and right channels creates a phantom center. Also, subwoofers are more about effects than reproducing notes. You can’t differentiate note pitches below 20 Hz anyway.  

Mixing for surround is kind of like mixing for stereo, except you direct audio files to multiple speakers. So, panpots are now surround panners (fig. 1).

Figure 1: Studio One’s Surround Panner.

Enter Dolby Atmos

Dolby Atmos is a bigger leap from surround than surround was from stereo. First, Atmos adds an element of height. Now you’re not just surrounded by sound, but immersed in a space. Second, Atmos isn’t audio, like a WAV file. Unlike surround, where your choices of where to place sound are limited by the number of speakers, Atmos is about metadata that places mono or stereo sounds in a virtual 3D world.

The optimum way to experience Atmos is with speakers, although that involves some complications and calibrations. For example, to hear sound above you, your “height” speaker (often part of a soundbar) bounces sound off the ceiling. You also need a room that accommodates multiple speakers. However, there’s a brilliant alternative to speakers: binaural sound through headphones. You don’t need a complex multichannel setup, because thanks to binaural audio, you can mix with Atmos and hear the results over headphones. After creating your mix in Atmos’s 3D space, just render that as binaural audio, and voilà—people listening to your rendered mix over headphones will hear what you heard as you mixed it.

Check out Dolby’s short YouTube demo while listening on headphones, and you’ll hear how well an Atmos mix gives a sense of space with headphones.

What Atmos Metadata Defines

Atmos differentiates between a Bed and an Object. A bed is very much like a massive stem based on a conventional, channel-based mix with specific channel restrictions—like 2.0 (stereo), 5.1, or 7.1 surround. (Note that Atmos supports multiple beds.) Conceptually, this is no different than using the console in previous Studio One versions, except that the mix for the bed can include elements that go beyond stereo. These include multi-channel panning for 5.1 or 7.1 surround, and multichannel-friendly effects (fig. 2).

Figure 2: The new Surround Delay is pretty wild—just wait until you try it.

Spatially speaking, the bed has a fixed position in space. For example, consider a movie, where characters are seated in a casino. The bed would consist of the casino sounds in the background, people talking, gamblers, and wait staff moving around based on conventional surround panning.

An Object is discrete mono or stereo audio that can be placed anywhere in the 3D Atmos space. It’s not tied to particular channels, like the bed, but is “floating in space.” For example, in the casino example above, James Bond could be an object. He walks down a staircase in the back of the casino, saunters toward the front, moves to one side of a baccarat table, stands for a while to observe the action, and then walks over to where he can find a seat. Atmos’s dedicated object panning makes it easy to have objects move around in your 3D space (fig. 3).

Figure 3: The Object Panner can move objects in a 3D space. You can automate these changes.

Another way to think of beds and objects is a band playing on stage. The drummer, bassist next to the drummer, keyboard player, and background singers remain at their spots on stage. They’re the bed. The lead singer who prances around and the lead guitarist who uses a wireless system to go into the crowd are the objects.

Metadata and Tracks

Atmos defines up to 128 tracks, including objects, to create the spatial field. For movies, this typically involves mixing 10 tracks for a 9.1 surround bed, and up to 118 objects. However, you can distribute the 128 tracks any way you want. This is where the metadata comes into play. It specifies location or panning data, including how fast an object moves, the level of the audio, and the like. Basically, it’s the audio’s traffic director, and routes audio in the 3D soundfield.

Rendering with Atmos

The Dolby Atmos Renderer included in version 6.5 complements and adds functionality to, not replaces, your usual workflow. It can convert your mix into any of several formats, including stereo or surround. For those without multi-channel speaker systems, Binaural Rendering (fig. 4) reproduces the effect of listening over a multi-channel loudspeaker system using headphones.

Figure 4: The Dolby Atmos renderer is rendering the mix to binaural. 

And we’re back to where we started: just as binaural playback reproduces the spatial sense of a real-world 3D space, it can just as easily reproduce the spatial sense of a 3D space created with Atmos. With Studio One 6.5 and headphones, you can start playing with immersive audio now.