Impulse Reverb

Friday, August 14, 2009 at 5:36 pm

Impulse Reverb is kind of obscure. Most sequencing packages don’t include IR out of the box, and there aren’t as many IR plugins as there are hall/plate/spring/whatever. If you haven’t heard of IR, you’re in for a treat — what the sampler does for sound, IR does for reverb.

Roughly: A starting pistol is fired in a dry room. The sound it makes is recorded. Later, the same pistol is fired again in, say, the sistine chapel. Again, the noise is recorded. Those two recordings are fed into the computer, and the computer subtracts the dry pistol noise from the reverb’d pistol noise. Voila, you have an impulse — a computer representation of how the sistine chapel changed the sound of the pistol. You can use that to get sistine chapel reverb on your drums, or anything else.

One supposes that this is done with a science-grade pistol, precisely engineered to emit the same bang every time. Really, though, you don’t need to be that exact. Tales abound of scruffy gentlemen undertaking guerrila reverbing recoinnoiters: A stereo pair of microphones is hastily erected in an off-limits area. A paper bag is inflated and popped. The scruffy gentlemen beat a hasty retreat, before security discovers them making loud bangs in off-limit areas. No word on whether a pair of microphones has ever been mistaken for an implement of terror.

If all this seems interesting to you, I recommend getting started with the free version of SIR and this collection of impulse collections. Just fire it up and start playing around; it’s easy to figure out. You’ll find that IR has similar limitations to sampling. If you pitch or time stretch a sample past a certain point, it sounds terrible, and IR is the same way. There’s not much you can alter after the fact.

Thanks to the vast selection of impulses available on the net, there’s no real need to make your own. However, I’ve always wanted to. It just seems like a super neat thing to do, in a nerdy, DIY sort of way. Writing this post has gotten my nerd juices flowing… So, I’m gonna do it! I’m gonna make some impulses. A wee bit o’ googlin’ brought me to this page, which has more than enough detail for me to get rolling.

I’ll post a follow-up, once I feel I have a handle on things. If anyone has any pointers, or drama-filled tales of illicit impulsing, please send ’em my way!

Categories: FX

One Comment on “Impulse Reverb”

Post a Comment