Inside Forza Motorsport, Part II: Making The Cars Sound Awesome

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On Monday, we took you inside Turn 10 Studios, the outfit that created Forza Motorsport and teamed with us on the Forzalopnik download pack. Now it's time for a deeper dive. This is how they make the XBox game loud.

We can hear the moaning now: "How," you say, "is this even remotely interesting? What's cool about an audio nerd shoving a Sennheiser up a tailpipe? I'm a busy individual. Can't you show me more burning Ferraris or something?"


OK, fine. We give. If you're really impatient, and if the idea of screaming sports cars doesn't get you all hot and bothered, then scroll down and watch the embedded video. We can wait. If that clip doesn't do it for you and you want to bug out, we understand.


There. You back? Crazy stuff, right? Good. Now check this out:

In a way, it's best to think of driving sims as being like the movies, where huge amounts of lighting and makeup are required in order to make people look exactly like they do in real life. Along the same lines, you cannot simply stuff an expensive microphone up the muffler of Hot Car X and expect to have your Xbox 360 spit out Glory Awesome Hallelujah. There's science involved, and funneling fake reality into your eardrums takes a lot of behind-the-scenes effort.


For a game like Forza, the audio job is nothing short of monumental. Forza Motorsport 3 ships with 400 cars, and almost all of them sound different. Exhaust resonance, the vagaries of intake and exhaust tracts, combustion-chamber design, firing order — there are a million different factors that affect how an engine sounds, and all of them are important. Complicating matters, no driving sim worth its salt duplicates a static environment. Wind, reflective surfaces, the location of the listener's "ears" in the digital world, vehicle damage, doppler shift — all of these things are pieces in the audio puzzle. Pay enough attention to the details, and you end up building a world-beating game like Forza or Gran Turismo. Ignore them, and you might as well be selling Pong to blind retirees.


Recordin' Ain't Easy, But It's Necessary

Because Forza's standard car library is pretty large — and because new cars are constantly being developed for online sale — Turn 10's sound team stays pretty busy. Every car that goes in the game is based on a real-life audio sample, and each of those cars has to be recorded under a strict set of conditions. Turn 10 samples an average of 50 cars a year; almost all of the cars sampled are privately owned, and most are sourced through enthusiast forums or friends of friends. Recording takes place on a rented chassis dyno, and because the game's cars aren't all in the Pacific Northwest (Microsoft's offices are just outside Seattle), the sound rig was designed to be portable. Everything is planned out in advance, but as one engineer put it, that plan is highly flexible: "We record a lot of cars that aren't [set for] the game," he said, "just because we can get our hands on them."


The hardware setup is relatively compact: A handful of microphones are arranged at varying points around the vehicle, and their signals are fed into a laptop computer running a version of the audio workstation Pro Tools.


The mic rig varies according to engine accessibility, fuel delivery, and throttle arrangement (carburetors get a mic shoved up against their chokes or velocity stacks, while fuel injection usually means listening from the mouth of an airbox), but on average, eight microphones are used per car. Particular attention is paid to accessory and induction noise — the whines and whirs of pulleys and belts; the honk of a wide-open throttle butterfly — as well as things like exhaust header and/or turbocharger sound. Dyno pulls are done at various rpms and throttle openings, with the resulting samples being mixed down, looped, and blended into a continous whole through the magic of software.

Crapcans, Crashes, and Caviezel

Naturally, there's more to all of this than just hanging out in a bunch of dyno rooms. Turn 10's sound team is responsible for Forza's complete audio package, which includes background music production and non-engine sound effects. Because Forza 3 offers damage modeling — and because car crashes make one of hell of a lot of noise — the Turn 10 guys got to put the hurt on some real cars. In order to do this, they bought ten rolling junkers of various shapes and sizes and took them to a rented test facility in Southern California.


This brings us to Mike Caviezel, Forza's lead sound engineer. Caviezel is a cheery, laid-back guy in his thirties, a former music major who moved to video-game sound effects after a stint recording low-budget rock bands. We were originally going to use his emailed thoughts as notes to write from, but they proved so entertaining that we figured we'd just post them in their entirety. Here he is on the gearhead crack that is the recorded crash:

Collisions! For our collision sounds, we actually rented a place out in the middle of the California desert that did government safety testing, but that could also recreate car crashes for legal and insurance purposes. We bought a bunch of shell cars — they only needed to roll straight — made of different materials like aluminum and carbon fiber, and we hooked 'em up to a sled that would send them rocketing into whatever we wanted, at whatever speed we wanted!

We'd tell the guys running the place, "Hey, how about an aluminum car going head-on into a concrete barrier at 60 mph?" They'd reply with a quick, "Yeah, sure give us an hour to set it up." And then we'd record it with about 20 different microphones, some outside the car, some inside the car in a special shock-resistant case we had built. Then we'd do it all over again: "Hey, how ‘bout a carbon-fiber car into a tire wall at a 30-degree angle at 40 mph?" "Yeah, sure, give us an hour to set it up…."

Awesome. Probably the most fun I've ever had professionally. I think I've still got the sunburn from those sessions.


Annnd that's just about the coolest thing since sliced impact-destroyed bread. Mike, we want your job.

Surprises, Or How Your Supra Is Quieter Than You Think

One of the most fascinating parts of all this is what we learned about audio hierarchy. Just because you can hear the thrash of a gearset from inside the cockpit doesn't mean that a microphone will pick it up. Weird things happen when you stick a high-fidelity mic into a car, and certain frequencies can play havoc with the end result. Surprisingly, spool and blowoff noises on turbocharged cars usually destroy recorded intake and exhaust noise — even the loudest fart-can Supra turns into a near-silent psshhh by the time it gets to tape.


Crafty tricks like intercooler-mounted contact microphones are required in order to pull intake snort from cars with loud turbochargers, but even then, the mishmash of noise can prove to be too much.


Naturally, Caviezel and the Turn 10 boys had a solution:

Recording superchargers, gear noise and turbos? We had this crazy rig built at a machine shop that would allow us to mount and spin various car mechanisms with a big ‘ol electric motor. The first thing we tried out on the rig was recording a couple of straight-cut gears. We mounted them on the rig with a braking mechanism hooked up to provide a load so that the teeth could [mesh as normal].

The first time we turned on the rig, the motor totally scrambled any electronic gear we had in the room. After quickly switching to a battery-powered recording setup, we cranked up the motor again and started spinning the gears, and it was exactly the sound we were looking for.


Of course, he then attempted to adjust a mic while the motor was running, shocked the crap out of himself, lost what he figures was a year of his life, and never told his wife. (His words to America: "Honey, I'm fine. Now.") We like this guy.


Being There: Dude, Your C63 Goes To Eleven

This is the cool part. No, strike that — this is the really cool part. In order to get a better idea of how the whole process works, we accompanied Turn 10's sound team to a dyno session in Seattle. We watched them record a mildly modified 2008 Mercedes-Benz C63 AMG; the car in question was borrowed from a local enthusiast, and it sported carbon-fiber airboxes, high-flow headers, a stock cat-back exhaust, and a few other tweaks.


The stock C63 is not a quiet car, but this one was absolutely insane — it was thick, crackly, and mean, as if the entire state of Alabama had been crossbred with a DTM car and an angry bull moose. Earplugs with a 20-decibel cut were not enough. Small children were sterilized. A week later, my ears still hurt. Caviezel called it "one of the best engine recordings I've ever heard."

Heck, don't take our word for it. Listen for yourself, but be sure to crank it through the roof:

Click to view

Imagine that noise being loud enough to cavitate your colon, and you'll get a pretty good idea of what it was like to be in the room. Which, naturally, brings us to volume. This is Caviezel again, on the loudest car he's had the pleasure of recording:

The loudest car I've recorded? I get asked that a lot, and there have been a few contenders (a NASCAR [V-8] on an engine dyno, a Chevy Nova straight-pipe dragster). Still, the loudest car I've ever recorded had to be a Porsche 996 GT3 Cup car with the race muffler removed. Hell, it was stupid loud before we took the muffler off.

That car was so loud that it made my chest hurt and my teeth chatter, and my ears rang for a good week afterwards. It's the the only dyno session we've done that got the cops called on us. The guys from the dyno shop felt kinda bad for their neighbors, but when we lit that thing off for the first time, we all smiled like naughty little kids. Again, awesome.


As he tells it, the cops got out of their cruisers, took one look, said "cool," and stayed to watch. Awesome doesn't even begin to describe it. Now if you'll excuse us, we've got a video to watch. Again. And again. And again.


Thanks to Turn 10 Studios for their hospitality and assistance with this story. No thanks to Turn 10 PR man Che Chou for making us wonder if we could sell everything we owned and add a C63 to the stable. Also, we're thinking of having a motor-driven gear rig built for our office so we can sit around and listen to straight-cut whine on our lunch hour. Is that wrong?

Jalopnik paid all airfare and lodging costs associated with this story.