How it works: spatial audio
Directional audio for AirPods Pro
YOU WILL LEARN
What spatial audio is and how it works
If you have AirPods Pro and iOS 14 you can get spatial audio, which changes what you hear based on the position of your head. It was rolled out to the AirPods Pro firmware in September 2020 and early reviews were effusive: John Gruber of Daring Fireball wrote that the effect was “very cool, very fun” and “very natural, not gimmicky or distracting. The spatiality just feels right.”
Spatiality? Let’s discover what spatial audio is all about.
WHAT IS SPATIAL AUDIO?
Spatial audio is a directional audio effect. In real life, if we move our head or our whole body then what we hear changes — so, for example, if we turn our head away from something that’s making a sound, we’ll hear less of it in the ear that’s furthest away. Similarly if there’s a sound above us and we look up, we’ll hear it more clearly because our ears are now better positioned to hear it.
Spatial audio brings that effect to your AirPods Pro. It tracks the movement of your head and adjusts what you hear accordingly. Apple didn’t invent the idea: you get very similar technology in Dolby Atmos for Headphones, which has been around for a while. And it’s part of the 3D audio tech that’s in the PlayStation 5 and Sony’s Platinum Wireless Headset. But spatial audio is Apple’s take on the tech.
WHY DOES SPATIAL AUDIO MATTER?
Think back to the last time you were at the movies. As you sat in the middle of a surround sound system the audio was all around you, so if a character spoke from either side of the screen you’d hear them in your left or right ear as appropriate; if something flew overhead the sound would do the same; if there was something behind you you’d hear it from the speakers behind your head, and so on.
As soon as you put on a normal pair of headphones or earbuds, you lose that surround effect. All you’ve really got is a left speaker and a right speaker, so sounds can either be towards the left, towards the right, or in the middle. You can mess with it a bit — pseudo–surround sound headphones use digital processing to create the illusion of surround sound using timing and audio effects — but it’s still just two speakers delivering audio that doesn’t change no matter what you
SPATIAL AUDIO TRACKS THE MOVEMENT OF YOUR HEAD AND ADJUSTS WHAT YOU HEAR
do with your head. With spatial audio, you get something much closer to the experience of sitting in a surround–sound movie theater. Audio sounds much more immersive and realistic, particularly with high–quality sound sources.
WHERE’S YOUR HEAD AT?
The key to spatial audio is the motion– detecting accelerometer in the AirPods Pro and the gyroscope in your iPhone. Together they track the motion of your head as well as the physical location of your body. For example, if you turn your head to the left the AirPods Pro detect that motion; if you move forwards or backwards or up or down, your iPhone detects that. That data is used to work out where you are in relation to the screen and adjust the sound field accordingly. If you move back from the screen the sound will get quieter, if you turn your head to the left it’ll make sounds from the left clearer, and so on. It does this through a combination of adjusting the stereo balance and making subtle adjustments to the frequencies of individual sounds.
CAN I GET SPATIAL AUDIO ON ANY HEADPHONES OR APPLE TV?
Sadly not. Without an accelerometer in your headphones your device has no way of tracking the position of your head, or at least it won’t have any way of doing it until Apple’s much–rumored AR glasses launch. Apple TV is a surround sound device but it doesn’t yet support spatial audio. So for now spatial audio is only available for AirPods Pro on devices running iOS 14, iPadOS 14 or later.
DOES SPATIAL AUDIO WORK WITH MUSIC?
It could, but we’re not hugely excited about it. Most music is mastered in stereo, not surround, so instead of taking a multichannel surround sound signal and turning it into positional audio you’d be taking a two-channel stereo signal and guessing what it might sound like in surround. If you’ve ever experimented with the faux-surround options in audio apps, Smart TVs or some soundbars you’ll know that such emulation is often pretty bad.
WHAT APPS WORK WITH SPATIAL AUDIO?
Any apps that support 5.1 or 7.1 surround sound and/or Dolby Atmos should work fine with spatial audio, and plug-ins should enable stereo apps to work with the tech too. At the time of writing spatial audio works on Amazon Prime Video, HBO Go and Hulu but not Netflix, which doesn’t support surround sound on iOS or iPadOS devices just yet. If you’d like to experience it in games, try Sayonara Wild Hearts in Apple Arcade.