Sub Rattlers

Prompted by Nathans post about rattling windows I thought I’d dig some files out of my library/archive that are related, but self generated rather than naturally occurring. But first the back story as to why I made these sounds….

Back in 2004 I was working on a horror film called Boogeyman – it wasn’t the greatest horror film ever made, we were stuck with a not-so-great VFX bad guy who really wasn’t very scary. We’d be working on the film for a month or so and had tried a lot of approaches as to how to make him more scary. We’d tried all the obvious approaches – stings, tones etc and were kind of stuck… Back then my kitchen & dining room was right next door to my laundry i.e. they shared a wall. I’d put some clothes in the tumble drier one night and set it going and when I went back to the kitchen I noticed all the wine glasses were rattling due to the vibrations from the tumble drier. Hmmmm I thought… This has possibilities – not in itself, I couldn’t record the glass rattles without the tumble drier in the background. But the idea was interesting….

I thought about it overnight & came up with this concept: what if just before the Boogeyman appeared, everything in the room began to resonate. If this happened in real life it would freak me out and in hindsight I guess an earthquake would be the only real way it could. But the next issue was how to generate the sounds in a way I could control them.

The next morning I did a quick experiment and realised I was definitely on to something, so I spent half the day playing with this new technique. Basically I took my subwoofer, a JBL LSR 12P, and lay it on its back. I then collected up a few props and very carefully lay them above the sub, supported so they could move/rattle without falling into the subwoofer. Then I got my SH101 analog synth and made a nice pure sine wave sub bass sound and played it through the subwoofer. Depending on how I bent the pitch, the subwoofer would pass through the resonant frequency of whatever object I sat near it. Wood seemed to have a narrow range of frequency whereas hollow metal objects and glass was broader & more sensitive to vibration. So I set up a mic and recorded the objects rattling as well as a split direct feed of the sub bass sound. When I came to use the sounds in the film I could check what sub was generating it and choose whether to use it seperately or not. And because the sub was so low in frequency it was very easy to use a HPF to filter the sub sound out of the rattles, so I ended up with discrete elements….

I processed some of the sounds further. In the film there is a scene where the hero is at an office party and thinks he hears the Boogeyman in the air conditioning duct. I got a 2m long piece of air conditioning duct and lay it on top of my subwoofer and it was easy enough to find resonance in it and make it vibrate like crazy. I then took some of those resonance recordings and printed them through impulse responses to give them some distance, and then printed the results of that through the Waves Doppler plugin. You’ll hear some of these sounds at the end of the soundcloud file below… Have a listen but be warned, if you’ve got a subwoofer prepare to have your room shaken up a bit… and if you don’t have a sub prepare to have your monitors distort as they try to replay some seriously low frequencies!


As with many techniques, the results vary greatly depending on what props you use, so I’m sure its a technique I’ll use again in the future when the occasion arises….. Its really a form of worldizing, except rather than re-recording the natural acoustics you are re-recording resonance… fun!

2 thoughts on “Sub Rattlers

  1. Ashok Gazula

    Hello Mr. Prebble,
    Loved the sounds of ‘Sub Rattlers’ that you recorded. Very interesting way to go about to get the objects to rattle by using your subwoofer, I would have never though of that method in a hurry 🙂 The Genelec 7050B Subwoofer used to always rattle my windows, in my former home studio, never thought it could be helpful to generate earthquake, horror, rattling SFX.

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