Jarvs: Almut, can you walk us through how a single operator gets its sound?
Almut: If something is already moving in-game, I’ll capture it, either record it myself or get footage from the team, and bring it into my audio software. Then I start experimenting.
I focus on what the operator is actually doing. Is it mixing liquids? Cutting? Stamping? I think about what’s moving, what’s interacting, and what that should feel like.
One important thing I’ve learned is that it’s much better to get something into the game quickly and iterate there. A sound that feels perfect on its own can completely fall apart once it’s surrounded by everything else. So instead of polishing something for ages in isolation, I prefer to test it in context and tweak from there.
And variation is crucial. If you repeat the exact same sound over and over, it quickly becomes irritating, at least for me. So once I have something that works, I build subtle variations to keep things rhythmic without becoming repetitive.
After that comes the fiddly part: dealing with the 3D game world. Operators are 3D sound sources, which means they have a defined size and distance in-game. You should hear them clearly when you’re close, but they need to fade naturally as you zoom out. That balancing act can only really be done once everything is live in the game.
Jarvs: I know nothing about the technical side, but I imagine it gets complicated when you have 20 operators next to each other and all those sounds are happening at once.
Almut: I wouldn’t say it’s technically complicated, but it’s a lot of fiddling to find the sweet spot where everything works nicely most of the time.
Mick: There are some aspects you wouldn’t expect. In most games, the “microphone” is positioned at the camera. That makes sense in first-person or close third-person games.
For Modulus, we had to do something different.
Because you can angle the camera downwards and zoom in and out freely, the sound can’t simply follow the camera. Think of it like a boom operator in film, holding a microphone just above the scene. That’s effectively what we’re doing.
There’s an invisible point on the ground that the camera looks at, and the microphone is centered on that point. As you zoom out, the microphone moves upward, but it stays aligned vertically above that spot. This works well for factory games, because once you have a lot happening on screen, you don’t always know exactly where a sound is coming from anyway, which lets us hide some imperfections.
The other big constraint is performance. You can’t just play sounds for the 5,000 objects that might be visible on screen. That would sound chaotic and break performance.
In some games, you can let overlapping instances stack or trim themselves automatically. We don’t really get that luxury. The sound has to work perfectly when an operator stands alone in an empty field, and also when it’s surrounded by hundreds of others. That balance is where the real challenge lies.
Beyond individual operators, there’s another layer at play.
Almut: We have a separate layer of general factory noise. When there’s just one operator on screen, you don’t hear that layer at all. But as more buildings and operators appear, that ambient layer gradually blends in.
Mick: We basically try to find a good average of what’s on screen. There are three main ambient tracks: a general factory layer, a conveyor-specific layer, and a nature layer, like subtle birds in the background.
These are evaluated at a fairly low resolution. We can’t calculate this per tile, it wouldn’t work performance-wise, so we approximate what’s happening on an island and blend accordingly.
Technically, the ambient system is sometimes “guessing” what’s happening on screen. But so far, nobody’s complained that the soundscape is lying to them.
Jarvs: From what I hear in the community, people really love that mix, especially the nature sounds. They say it adds to the zen feeling. It’s not just a mechanical factory hum; there’s a sense of space and calm.
And it works beautifully with the little environmental details Antoine has added visually. It makes Modulus feel like more than just a factory, it feels like our factory.
Mick: It works great… until we add the next batch of sounds. Then we go through the entire process all over again.
But it’s good to hear that right now it feels like we’re in a good spot.
That’s a closer look at how operator sounds are built and layered into the living, breathing rhythm of your factory. From individual clicks and movements to the full soundscape of a working production line, it’s all about subtlety, timing, iteration, and restraint, making sure the factory feels alive without ever overwhelming you.
If you missed Part 1, make sure you check it out. We dive deeper into the philosophy behind the overall sound of Modulus and how we shaped its calm, clockwork identity.
And if you’re curious how all of this feels in motion, you can try the updated demo right now as part of Steam Next Fest.
Thanks for joining us for another Deep Dive. We’ll catch you in the next one.
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— Team Happy Volcano