Brad's Sonic Musings

Tag: sound design

  • Adventures in Foley: The Tumbling Machine

    A few months ago we were recording some sounds for inFamous Second Son, when I realized how challenging it is to get continuous debris recordings in a tiny recording booth. Inspired in part by the ArenaNet team’s field recording journal from Guild Wars 2, I started to think about a way to be able to record long continuous debris recordings and, lo, the Tumbling Machine was born. I call it the Tumbling Machine because that sounds impressive, but really it’s ridiculously simple, yet pretty damn effective.

    I started with a giant plastic garbage can. The issue there is that the molded handles on each side prevent an even roll, so I cut them off with a dremel tool. Now it rolled nice and smooth but the plastic surface would obviously color the sound of the debris. To counteract the resonance of the plastic, I bought a package of eggcrate foam that you put on top of a mattress and lined the bottom and sides of the trash can with it. I tried a few different methods to affix it, but found the most effective was gaffer tape (duct tape would work fine too). The foam did a great job of insulating the impacts so you get the debris, with very little coloration from the plastic. The drawback, is that the foam can trap smaller particles of concrete, wood, glass or other debris you may want to record, but worse off, you could always replace the insulation each time you record a different surface. Here’s a short movie detailing the construction and use of the Tumbling Machine. In this instance, we were using it to record concrete rubble sounds.

    It’s a cheap, effective way to make clean, continuous debris movement sounds. Here’s a capture from the concrete recording session cleaned up, so you can hear the results:

    The one issue we’ve had is that the debris spills out as you roll the trash can. I’m planning on cutting a fairly wide hole in the lid of the can (so a blimp can fit inside without hitting the edges during tumbling), and cover the inside of the lid with foam to prevent coloration and try to keep the debris inside. Hope this inspires someone to make their own Tumbling Machine or maybe even something more outlandish/useful. Happy Tumbling!

  • Creating seamless loops in Sound Forge

    This is a simple trick I’ve used for years. It’s straightforward, but my designers and interns I’ve showed it to have appreciated it as a quick, easy, intuitive way to create seamless loops every time.

    This method is useful mostly for static sounds at least a few seconds in length. It works great for ambiences, environmental effects like fire, wind, steam, water, or lasers, and even for sports sounds like skateboards, snowboards, and car engines at constant rpms.

    Also, of course, this method will work in any audio editor or DAW. Sound Forge is just my wave editor of choice, and for me at least it’s the easiest way to quickly make seamless loops. So that’s where the screenshots hail from.

    Step one: Design a longer than desired sound!

    The first thing to do to make a seamless loop is to design a sound longer than you anticipate using.  Basically what we’re going to be doing is hacking off the end of the sound and crossfading it into the beginning, so if you’re planning on having a 4 second looping sound, design a sound that’s between, say, 5 and 8m seconds long.

    picture of a 6 second wav file with the last 2 seconds of sound selected

    Step two: Find a zero crossing in the file where you want the end of the loop to be

    Again, let’s say we want our sound to be roughly 4 seconds long, so go to the 4 second mark of the file and search for your nearest zero crossing.

    zoomed in picture of a wav file with the cursor at a zero crossing

    Step three: Cut off the tail

    Once you find the zero crossing nearest where you want your loop to end, select from that point all the way to the end of the file.  Drag this section of the file (the tail) to the Sound Forge window to make a new file from it. Be sure to note how long the tail is.

    picture of 2 second end of wave file copied to another file

    Step four: Fade the tail

    Select the entire tail file and do a -3dB exponential fade out.

    Exponential graphic fade out

    Step five: Fade in the head of the loop file

    Now, remembering the length of the tail file, select that much of the head of your looping file, and do a -3dB exponential fade in.

    exponential fade in on the beginning of a wav file

    Step 6: Mix the tail into the head

    Now select the tail file, and drag it to the beginning of your loop file.  Make sure the file is set to loop, play it back and voila! A seamless loop.

    mixing the tail end of the file into the faded in head of the file

    Final thoughts

    Bear in mind that, like any looping sound, what matters most is the design of the source file.  If you have a bunch of aspects in a short looping sound that give it “character,” it more often than not will result in a sound that is very apparently looping.  Furthermore if your loop contains rhythmic elements such as a skateboard clacking on a sidewalk or a laser oscillating and humming you need to ensure that your loop timing is set up to perfectly match the rhythmic timing of your sound.