Call Of Duty Modern Warfare II Team Broke Multiple Microphones Recording Gun Sounds, Says Stephen Miller

How do you design sounds for an FPS? Anyone who’s seen these viral videos of someone accidentally whipping themselves with a gun will tell you it’s a lot more complex than just pointing an iPhone at a glock to make a gun sound like, well, a gun .

Stephen Miller, Audio Director, Infinity Ward

We spoke to Stephen Miller, Audio Director at Infinity Ward, about all the intricacies of making gun sound the way it should be, and the high cost of broken gear that could come with such a dangerous undertaking. .

The biggest takeaway is basically how Infinity Ward broke the physics of what a gunshot sound really is, and how much technology is coming into the new Call of Duty to blast enemy combatants into authentic songs, rather than a single WAV file on disk.

This generation of consoles puts a huge emphasis on 3D audio, especially with the PS5. When you were mixing sounds for MW2, were you doing it with 3D audio in mind?

Stefan: Well, we’re still mixing, but yes, we support 3D audio on PlayStation as well as another version on consoles and Windows. When we mix, we need to make sure everything sounds good on everything from stereo TV speakers to full 7.14 surround sound. We absolutely make sure it sounds good on everything.

Considering the Modern Warfare series is one of the most narrative Call of Duty series out there, what was it like having to choose between having something more cinematic and making it work better for gameplay?

Stefan: We’re trying to make a game. MP, SP, Co-Op all sound different, especially anything that gives gameplay feedback. Footsteps, guns, whatever is supposed to give you some sort of feedback you need to pay attention to what’s going on. In the campaign, we will have a cinematic moment and we will exchange custom sounds just for that.

It’s more for big stages. Helicopters flying and shooting at something, or a big tank. More artillery than small arms. But we had, where if we have a slow motion or any kind of special scene in the campaign, we’ll also do custom sounds for that.

Call of Duty Modern Warfare 2

Speaking of tanks, I was surprised to see that you were using real tanks for the effects.

Stefan: We did a lot of recordings for this project. 3 helicopters, various tanks, artillery, all small arms, rocket launchers. You name it, we tried to record it.

So, having done all of that, explain to us what makes something look like a tank then?

Stefan: When we record these things, we usually record close-up and record on 50 to 60 different channels. Some of them are stereo microphones, some are mono. So you’re looking at somewhere between 30 and 40 microphones at varying distances. And then additional microphones at further distances to get that perspective as well.

Getting a tank to fire its main gun isn’t exactly cheap, so we tried to optimize the registration as best we could.

When we break down a weapon as a player, from this perspective: there’s a gunshot, there’s the mechanics of it – the rattle of metal. There’s the low frequency effect, the big bass rumble, and then we have the tail or the projectile, so you hear it go off in the distance.

And we break it all down into individual parts using different types of mics and placements to get all of these individual sounds so that when you pull the trigger and go bang, we get the 4 plus you get our reflection system.

It’s ray tracing that spans the world, it finds points to interact with from Geo on the side of a building or a mountain in the distance. It will play a reflection sound on these. Every time you pull the trigger on a gun, be it a tank or small arms, you get 12 or 13 sounds playing at once. Everything forever changing, everything forever making you feel like you’re in your environment so it’s not repetitive. It’s natural.

So it uses geometry to indicate the type of sound it plays?

Stefan: Yes. In this way we acn also make different sets. So if you’re in an urban environment you get different kinds of reflections than if you’re in a big open desert.

Regarding the ray tracing you mentioned, does it use the same technology as graphical ray tracing?

Stefan: It’s similar. All of this means that it has a source and it reaches out and draws a line mathematically until it reaches a point or geographical area in the world. It is a cheaper version of a ray than what is used for the visual part. They go off often. Each time you fire an automatic weapon, it fires a beam. He makes a mark.

So the previous generation consoles would use it too?

Stefan: These traces are very inexpensive so a lot can be done.

So having all these mics near guns that fire is kind of like having a baby in front of an alligator. How was it?

Stephen: I’ll quote you on that at some point [laughs]. Different microphones have different SPL levels and have different uses. We have to be very careful and we have blown up microphones in some of our recording sessions. So basically you put something a little too sensitive too close to something that has a high SPL and it blows the diaphragm – done.

Over the years and through lots of experimentation and a few failures, you will learn what can be where depending on the volume of something. If we’re talking about suppressed weapons, a lot of this stuff can come very close because it’s not a lot of SPL.

The second the suppressor fires, you back up a bit. As you go into bigger caliber things, you drift further and further away. We have certainly had failures.

When we record in the field, everything is inside what we call the Zeppelin. Above there is the blur or the hair for the wind. It really helps, so if it’s windy, it doesn’t hit the diaphragm and cause that fluttering sound.

Is there anything about the sound that you’re particularly proud of?

Stefan: There are definitely things that I gravitate toward. This can be an edited scene or a running sound for multiplayer. Jake has been working on these and there are some that are like “oh this is so incredibly satisfying”. I know that when I go to play, I will want this operator with the one assigned to it.

There are also some weapons that I’m absolutely in love with, not because they necessarily work well, depending on my playstyle. Just because I like the way it sounds and want to hear it again and again. Again.

We put a lot of love and care and sweat and tears of blood into the weapons every step of the way from how they’re chosen, animated, recorded, how sounds are created, how they’re mixed in-game It’s really important to us.

Do you have something to say to APAC fans?

Stephen: There are many exciting things to look forward to. We also have a lot of new technologies in MW2. We have a brand new occlusion system. When geometry gets in the way, it gets in the way [the sounds]. We have a brand new convolution reverb system. It’s especially fun for us because it lets you go to a place and add the right reverb to it. You can save a pulse there. If we’re going to find a particular warehouse and think it sounds good with reverb, we can go in and capture an impulse, and take a recording and it drops right into the game and every sound is processed into that reverb.

Rather than trying to do it synthetically with some sort of reverb, you get something really natural.


With Call of Duty Modern Warfare II releasing in October, there’s a lot to look forward to. With a focus on an immersive sound experience, it’s definitely something you’ll want to check out with headphones at least once.

Thanks to Stephen for sitting down and chatting with us, and be sure to also check out our other Call of Duty Modern Warfare II interview.

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