Crash-in-the-Box

The humble Crash Box: From cookies to crashes in 1,500 calories, and tasty either way.

A “crash box” is a device to simulate the sound of, well…a crashing something. Originating in theater and radio productions, it’s a container with debris in it. You drop it, it crashes. You roll it, you get a slow trickling of debris. Simple enough.

It’s something that an aspiring sound designer sees mentioned a lot in books and articles, but which “serious” sound designers might not use much. Why use a crash box when you have the budget to go to a junkyard and drop real cars on one another? Well, with no car-crash scenes or budget in sight, it still sounded like destructive fun, so I just had to make one.

This past winter I got just the perfect container: a cookie tin from an appreciative design-industry acquaintance. The goal is to fill the container with glass, ceramics, rocks, busted-up bricks, sticks…pretty much whatever you’d want to have make noise. I picked debris that would best simulate a car crash: glass, plastic, ball bearings, metal bits, and rubber. The cost was US$0.00, unless you count the 4 cents of gaffer’s tape I used to hold the lid on.

I recorded breaking those glasses separately before adding the debris to the crash box…which I also, of course, recorded as I poured it in. To get a bright sound with a low noise floor for the subtler tinkles and debris sounds, I used a large condenser microphone for these individual bits. I just had to break a coffee mug too, to see how that sounded. OK, fine: Two coffee mugs.

Test time had arrived! I often record quiet sounds in a wool-carpeted dressing room in my house, since it’s the most acoustically dead free space I’ve got. I didn’t want the impact sound to pick up concrete or wood on impact, so the carpet was a good choice (sound blankets would have done in a different environment) I held the crash box above my head, right up against the ceiling and dropped it, tracking the loud crashes with a both a large condenser mic (farther away) and a small condenser mic up close.

Such sweet mayhem! The raw recording it doesn’t quite get there in terms of realism, but mixed, shifted, and layered, crash boxes do make fantastic elements for any sort of destructive needs. Today’s sound is an example of several crash box clips and a few other “sweeteners:” the aforementioned breaking glasses, one low-frequency effect, and the sound of me kicking the door of a ruined pickup truck. To me, it sounds like a sonic illustration: maybe not perfectly photo-real, but evocative and expressive.

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[Røde NTG-2, Røde NT1a, and Oktavamod MK012 mics, Fostex FR2-LE recorder (various sessions)]