Uncharted games are often compared to the Indiana Jones movies for the obvious reasons: witty comebacks, treasure hunters, close calls, fist fights, and just a bit of the supernatural.

But there’s another good comparison often overlooked. The Uncharted games are some of the most polished games out there. For a game to feel polished, everything has to be in place; anything out of place breaks the illusion. Texture pop-in and models colliding can be pretty easy to spot, but sound is just as important to maintaining the illusion.

We had the chance to talk to two members of Naughty Dog’s sound team to find out a bit more about what goes into maintaining that illusion: Phil Kovats, the Audio Director on Uncharted 4, and Rob Krekel, Senior Sound Designer. Both have been with the team quite a while – Kovats has at least contributed to each of the four Uncharted games and was the Senior Sound Designer on Uncharted 2, while Krekel joined the team for Uncharted 3, The Last of Us, and is now on Uncharted 4.

By this point, Naughty Dog is, to say the least, experienced with Sony’s platforms, and they’ve always managed to push systems pretty hard. For Uncharted 4, the sound team has access to a few big advantages they haven’t in the past. The ATRAC9 codec, which is the newest version of Sony’s long-running ATRAC codec.

ATRAC was initially developed to fit a CD’s worth of music onto Sony’s proprietary minidisc and later used as a digital compression format for Sony’s music devices. ATRAC9, however, is a game-specific codec introduced on the PS Vita designed to keep memory and CPU usage as low as possible.

This, Kovats explained, is allowing the team a lot more fidelity with sound and giving them a lot more room for sound detail.

“More physics, more action, more motion of sound, the way sound works in the environment,” Kovats said, listing off a few of the benefits.

“And then vehicles!” Krekel interjected. “The jeep is something new for us entirely – there hasn’t been something like that since the [Jak and Daxter] games.

“It’s a fully physics driven model,” Kovats explained, using things like Crankcase’s REV middleware, which is code focused specifically on helping game designers make car sounds feel more organic to the player.

“So with the vehicle we have the wheels moving, real-time suspension, rattling,” Kovats says.

Each wheel, Krekel says, can interact separately with a surface. If the front right wheel’s in the mud, the front left is on asphalt, and the rear tires are on sand, they’re going to be spitting out three different sounds from four different sources.

The PlayStation 4 also allows the team to make better use of granular synthesis. Granular synthesis lets the team do things like spread a single sound out into a surround-sound type of soundscape or to make background noises sound more organic. Instead of just playing “engine_sound.wav” or capturing every possible variation of acceleration, braking, and whatever else, they can use the same set of samples to create different, more believable variations of that sample that fit the different situations the game presents.

Each sound in the game has a bunch of little pieces of metadata pinned to it that helps it tell the game engine know how it should sound to the player, whether it’s moving, behind a door, around a corner, or in or outdoors.

The scene we see in the trailer above, Krekel and Kovats both agree, is one of the most challenging the team has had to put together.

“Just the jeep alone has been an enormous challenge, getting it all to work. All the systems came online slowly. Okay, we sort of have the engine working, but we need to work on the physics, because the physics are what make the sounds behave differently, then we need to get the tires playing at all, now it’s different tires on different surfaces… just this big long evolution of getting it to sound right.”

The team has already put a lot of work into the game and has tons more ahead. They only used one asset from the previous Uncharted games. A gun’s a gun, right? The only thing that’s carried over, though, is the sound of the AK-47 reloading. Krekel had to remaster the original recordings first, and then integrate it into the other sounds the gun makes when it fires, when Nathan knocks a clip out of the rifle. The sound when he cocks the gun, though, that’s the same sound we heard in the original Uncharted – a small fragment of history linking this new generation Uncharted to its ancestors.

As you watch the trailer, it’s easy to focus on the surface sounds – Nathan talking, guns firing back and forth. The kinds of sounds that really help Uncharted shine are a bit harder to spot. The way the sound bounces off the walls when Nathan reloads his pistol indoors. The sound of the grenade clinking on the ground next to him. The way the car sounds in the grass versus grinding up a muddy hill. There are tons of details that we as players don’t ever really hear consciously but would miss if they weren’t present, especially in a game that feels as real as the Uncharted games do.

I’m looking forward to trying to play the game with my eyes closed, whether I’m in an action scene or one of the game’s vehicles – Kovats confirmed there would be more than one – when Uncharted 4: A Thief’s End hits in 2016.