GAD 03: Hoverbike Passby
Let’s keep going with the Sci-Fi SFX. This GAD is a futuristic hoverbike passby, complete with droning and electrical sparks from the hover engines.
Here’s the breakdown of the sound. Note: I’ve disabled volume automation and panning on some layers so that you can easily re-use individual layers in your own projects if you wish.
What Makes a Passby Sound Like a Passby?
Because most of the layers of this sound are quite straightforward to recreate, let’s understand why passbys sound the way they do by exploring a few key concepts. If you don’t apply these techniques, you may have the coolest sounding hoverbike or spaceship in the world, but it will sound like its parked next door rather than sounding like it’s zooming past you at incredible speeds.
To achieve this effect, you must keep in mind three simple things:
- Volume automation
- Pitch automation (Doppler Effect)
- Panning
Volume Automation
Volume automation is important for obvious reasons: an object in motion will sound quiet at a distance and grow louder as it approaches. The important part here is to get the shape of the automation curve to be correct.
Notice how there’s a distinct peak at the center and therefore the curve is not linear. This simulates that the bike is spending the least amount of time directly next to the player, and therefore giving the impression that it is moving very fast.
Pitch Automation
Pitch automation is being used to simulate the Doppler Effect. You may not know it by name but if you’ve ever sat in a car on the highway you would have noticed that cars passing by you will pitch up and down as they do so. The pitch automation curve is very similar to the volume automation.
Panning Automation
Finally, panning is needed to simulate the direction that the bike is moving in. In my example, it is left to right. The important thing here is to understand that the shape for panning will be different compared to the shape for volume and pitch.
However, those with a keen eye will notice that the only reason for this change is because the x-axis here represents hard left (100%), center (0%), and hard right (-100%), and not simply 0–100. Therefore, the shape is exactly the same and it creates a peak in the middle even if it doesn’t look like it because it is adjusted to match the format of the panning automation clip.
An easier way to understand this curve (and the previous two) is to think that it works exactly like an Attenuation Sphere in a game engine: the sound volume will increase at a much slower rate if you’re away from the source, but the rate will increase as you move closer to the center. Essentially it’s an exponential increase and this is what we want.
Note: most if not all modern game engines automatically take care of volume and panning (3D sound) and have a built-in Doppler Effect modulator, so you may want to check with your team if you want to bake these mods into your sound. On the other hand, if you’re making audio for film, a cut-scene, or a game trailer, these techniques will work flawlessly.
Drone
Lets begin by analyzing the drone sounds (for lack of a better name). These 2 layers form the majority of the character of the passby. Drone 1 was made in Xfer Serum with the sole purpose of achieving that classic sci-fi sound often used for vehicles, which resembles helicopter blades. To get this effect, it is necessary to modulate the volume from 0 to 100 very fast. Of course, this was accomplished by assigning an LFO to all of the relevant Level (volume) parameters, which you can see highlighted in blue in the image below. With this done, all that remained was to go crazy and try out all types of wave-tables, filters, and effects, pretty much at random until a cool sound came about.
Don’t be afraid to break all rules of typical sound engineering and mixing and crank those knobs up to 11. If the sound is massively distorting, that’s just a gateway to interesting and unexpected results.
On the other hand, Drone 2 is a loop that I found in one of my libraries which already had this “helicopter” quality. I used it because it had a nice mid-range, warm, engine-like tone that very well complements Drone 1. A little bit of reverb makes it seem like the source of the sound is at a distance.
To add an extra layer of verisimilitude, I took a recording of a real-life Dodge Challenger passby, slowed it and pitched it down to accentuate the engine pops and rumbles, and called it a day.
Engine Rumble & Sparks
At this point, the sound is built enough to give an idea of what it’s supposed to represent. However, it is missing the bold, powerful, design choices that make the difference between a recording and a designed sound.
The “engine rumble” is actually just a massively distorted and bass boosted explosion sample of some sort. The source is not really important, all that matters is that it has a nice grainy texture with a lot of low end. After this basic processing, I reversed the sample and automated the volume to gradually increase. I used a similar bass-y impact effect for the follow-through, after the bike has surpassed the spectator.
In a similar fashion to Drone 1, the Passby Engine layer makes use of LFOs to modulate volume. However, being that the source sound is a sample rather than a VST or synth, the LFO must be added via channel effects. I used FL Studio’s built-in Fruity Peak Controller, which also has an LFO section, and then linked the Volume knob in the channel settings window to the LFO Speed knob in the Peak Controller with the Link to Controller setting. At this point, I was able to automate the LFO Speed knob to change gradually slow down the rate.
Last but not least, for the sparks I layered multiple electrical sound effects until I reached an interesting overall mix, and then topped it all off with some reverb.
Originally published at lfaltoni.wixsite.com.
