Check this interesting article at Jalopnik featuring the car recording sessions for “Forza Motorsport 3“.
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.