Spatial audio has traditionally been a speaker technology, but it has come a long way. These days, you can get proper spatial audio with most headphones and even some earphones (like Apple’s AirPods Pro). But head tracking is still a relatively new feature, and many regard it as a gimmick. So, what is head-tracked spatial audio, and how does it compare with fixed spatial audio?
Fixed spatial audio creates 360o sound around you, so it seems like all the sounds are coming from different directions. Head-tracked spatial audio does the same, but it uses motion sensors (usually located in your earphones) to change the direction of the sounds based on the position of your head.
Of course, our listening experiences are immensely personal, and we all have preferences, so there’s no “right type” of spatial audio. Both have their pros and cons and unique use cases. Let’s examine fixed- and head-tracked spatial audio more closely.
What Is Fixed Spatial Audio?
Fixed spatial audio is “traditional” spatial audio. It evolved from Surround Sound, a system where a set of speakers would surround the listener, each playing a different track, making it seem as if the sound is coming from all around them.
Fixed spatial audio improves Surround Sound by giving the listener a full 360o audio experience. It accomplishes this through multiple speakers, advanced algorithms, or a combination. The technology is popular in movies, TV shows, video games, and music, which is why many companies have incorporated it into their offerings. These include Dolby, THX / Razer, and Apple.
It offers a more immersive experience than standard stereo audio. For example, when watching a movie, you can hear the exact direction that sounds are coming from, like a helicopter flying over your head or explosions going off far in the distance. It’s not just directional, but it can also simulate distance to some extent.
However, fixed spatial audio doesn’t change direction based on the position of your head. When you’re watching a movie, and you turn to someone sitting next to you, the direction of the sound doesn’t change, causing some loss of immersion. Sounds that should be coming from the left when you’re watching the screen will still be coming from the left when you look away.
What Is Head-Tracked Spatial Audio?
Head-tracked spatial audio works in precisely the same way as fixed spatial audio. You get a full 360o audio experience when watching movies or shows, playing video games, or listening to music. This effect is created by multiple speakers and advanced playback algorithms.
There is only one difference, but it’s significant: the sound will change position as you turn your head. Motion sensors will tell your headphones or earphones when you move your head, and the system will adapt accordingly. This creates an even more immersive experience.
For example, when you’re watching a movie and turn your head to the right, sounds that would have been on your left will now sound like it’s behind you. When you look down, sounds from the front will come from above.
It’s more realistic than fixed spatial audio since that’s precisely how we perceive sound in real life. If a speaker to your left is playing music, turning your head to the right will put that sound behind you. In that sense, head-tracked spatial audio is a massive step forward from fixed spatial audio.
Which One Is Better?
In theory, head-tracked spatial audio is much better in every way. It simulates a realistic listening environment that changes according to the orientation of our heads and the direction we’re facing.
Our brains are incredible machines. They can get absolutely invested in anything they perceive as accurate. However, it takes just a tiny mistake to break that realism and remove us from that experience. That’s what happens if the sound doesn’t change when we move our heads since our brains realize the directions should now be different.
This immersion and added realism are great for many use cases. For example, gamers can realistically pinpoint opponents or the locations of sounds, even if they look away for a moment. Movies and TV shows become more realistic since your aural sense will pick up the sound in a realistic way even when you’re not looking directly at the screen.
Unfortunately, both of those scenarios are still flawed. Your hearing might try to convince your brain that the sound is real, but your eyes still look away from the screen, breaking the immersion.
Where head-tracked spatial audio truly achieves its full potential is when you’re listening to music, preferably with your eyes closed. If your music app supports it (like Apple Music does on many tracks), you will hear the band or musicians all playing from different directions. Moving your head will change those directions in a realistic way, adding incredible depth to your music.
Head-tracked spatial audio is better than fixed spatial audio in almost every way. But that doesn’t mean it’s perfect.
The Flaws of Head-Tracked Spatial Audio
As great as head-tracked spatial audio is, it has a few problems.
It’s Not Perfect
Most spatial audio devices with head tracking will assume that your head’s position when you start the playback is the default “forward” position. As someone who likes to listen to music on my iPhone and AirPods Pro, even when I’m working, I often keep my iPhone on my desk, just to the left of my computer.
When I start playing a track with head-tracking spatial audio enabled, I’m obviously looking slightly to the left since I’m focused on my iPhone. When I turn my head back to the right to face the computer, the sound seems to be coming from the left, which is slightly frustrating. It autocorrects after a minute or two, but it is distracting.
Running with your AirPods Pro or other head-tracking earphones can also be problematic. The music will play beautifully until you reach an intersection and have to turn your head to look for traffic. I’ve found that it can take a few seconds for the earphones to notice that I’m facing forward again, but those few seconds can be a pain.
Not Everything Supports It
Spatial audio is still not widely supported, and head tracking is even less. Depending on the technology you use, it might not work perfectly, or it could not work at all. Modern devices in the Apple ecosystem cater to it. If you have compatible AirPods (like the AirPods Max or AirPods Pro 2nd Gen) and use Apple Music on your iPhone, it should work without issue.
However, even in that scenario, not all music supports spatial audio, let alone head tracking.
Some Sound Engineers Don’t Approve
Sound engineers can spend a lot of time getting the audio mix just right in both music and film. They might determine that they want a particular sound to come from a specific direction, and then they implement it that way. This means that some sound engineers are frustrated to no end with spatial audio (especially if it includes head tracking) since it changes the effect the sound has on you.
Conclusion
Fixed spatial audio is an excellent feature that increases your immersion by creating a 360o sound stage. Head tracking enhances this feature even more by changing the direction of the sound as you move your head.
Some people love head tracking, while others prefer to use fixed spatial audio. It is a matter of personal choice and preference in the end. Head tracking can be distracting to some users. Thankfully, it’s a feature that you can quickly turn on or off, so you can get earphones or headphones that support head tracking, then disable it if you find you don’t like it.
