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November 03, 2016

When a Tree Falls in a VR Forest: Sound Design in Robinson

by Audio team (Contributors: Christian Schilling, Principal Audio Designer and Jonas Obermüller, Audio Designer)



You've seen the horror films. A group of people are lost in the woods, and they are terrified. The woods are full of sounds—birds; rustling leaves; cracking, creaking branches; wind—but no one notices until it goes silent. That's when everyone knows something has gone horribly, horribly wrong. It makes a good metaphor for audio engineering in games. When the audio is doing its job, it helps immerse you in the world of the game, and you take it for granted—most of the time, you won't even notice it. But when something is off, the entire world feels wrong.

Because game audio is most noticeable when it's not working, a lot of people don't realize how much work goes into it. When a game has good audio, it tends to become invisible, the kind of background noise that you are used to hearing and blending out all day every day. But that background sound track is part of what makes up the real world, so a game needs to mimic the effect in order to truly immerse the player.

In VR, audio engineering becomes even more important—a deciding factor in whether or not your brain is going to buy into the virtual environment your eyes are telling it about. If the sound can help convince your brain, you are less likely to experience any sort of VR sickness-related discomfort. In Robinson, we used 3D audio, which means that sounds are placed in specific locations around each level, growing louder or quieter depending on how close the player is to the source of the sound. Together, all of these sounds create a realistic background ambience that really brings the world to life.


Not only did we use audio in Robinson to bolster the atmosphere and mood of each level, we used it to foreshadow some of the things you are going to encounter later in the game, and to guide the player. 3D audio can be a really effective tool for directing the player's gaze in VR. Because a VR player can look anywhere at any time, it can be difficult to direct them through a level in a particular way. But if you are walking through a virtual forest and you hear a loud crash behind you, you are probably going to look around for the source of the sound because thanks to HRTF (head-related transfer function), a player can tell exactly which angle a sound is coming from in a virtual environment.

HRTF allows players to determine whether sounds in the game world come from above, below, in front of, or behind them – just as we can in real life. This adds a whole new dimension of immersion to the game; you feel a much stronger link with the virtual world around you, and a sense that life exists beyond your field of vision. VR also requires audio designers to focus more on adding authenticity to the proximity of sounds, as players will instinctively feel that the closer they get to a sound source, the more its properties should change. This means more sophisticated attenuation behaviors have to be built in. So, for example, as you get closer to Laika's face, her breath gains an extra crispness. The same thing goes for the sounds the raptors make as they come in for the kill—the way the sound changes as they get closer makes it an extra scary moment. And none of this would be possible to the same extent in a traditional (read: not VR) game.

If a tree falls in a forest and no one is around to hear it, does it still make a sound? ( Maybe.) And if a virtual tree falls in a virtual forest, and you're looking in the other direction, does it still make a sound? (Yes.) And is that sound actually a recording of a tree falling? (No.)


When there is a sound in a game—whether it is a tree crashing to the ground in a forest, the roar of a T-Rex, or a spaceship taking off—the brain tends to accept it as being the thing it's representing. Even though most of the sound effects you hear in games and movies are often anything but recordings of the real thing. A sound needs to feel real, but it doesn't need to be a recording of the real thing. In Robinson it was no different. As soon as we had concept art for the game, the audio team began experimenting with sounds and collecting layers to create an audio ambience that mirrored the proposed atmosphere of the game.

The very first sound we created started out as a recording of a cricket. But, of course, we didn't use the cricket recording as the voice of an in-game cricket. Robinson is set in a sci-fi world, and we're talking about sound engineering after all; nothing is what it seems. So we took that cricket recording, lowered it three octaves, slowed it down, and suddenly, we had the first layer of the ambient sound for the Jungle area. We find sounds for games in the most unlikely places.

The roar of our T-Rex is probably the best example. Take a look at our first Robinson trailer. (What do you think the roar of the T-Rex is made of?)

Any guesses? If you thought about lions roaring or the guttural—and freakishly loud—cries of a howler monkey you'd be wrong. We experimented with bird sounds and car engines, but our T-Rex's voice was created by layering—among other things—a pitched down car horn and a really creaky door. The voice of our Capreasaurus is part electric toothbrush, something that made it sound more hysterical and scared. In the end you can't tell that you're hearing a horn or a toothbrush because it is all blended and layered together. When you see the T-Rex in the trailer open its mouth and hear it roar, it sounds like a dinosaur roaring. Not that anyone knows what that actually sounded like.

In order to make a game feel realistic, it needs layer upon layer of ambient sound that mirrors the real-world experience, be it the background noise of the jungle or the roar of a dangerous predator. This is true of any video game, but is even more important in virtual reality, where good sound engineering can help reduce VR sickness and make players feel deeply immersed in the world of the game.

When Robinson: The Journey is out, we're confident you won't believe your eyes when you first see the fantastical landscapes of Tyson III stretching off into the horizon. Hopefully, though, you'll believe your ears – a surefire sign that we've done our job creating a soundscape that makes you feel truly present in a new world.