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5 Tips for Better Game Audio

May 8, 2015

5 Tips for Better Game Audio

It’s time to come clean. Despite best intentions, we don’t always spend enough time on sound.

We often settle for 99 cent stock sounds in our games. And yet we all know that while a UI can look great, character animations slick, environments beautifully textured, if a game’s sounds are too obviously ‘stock’, the overall quality suffers.

Is there a way to work within the constraints of budget and time, and still make great sounds for our games?

The obvious answer is to make the most of your sound assets - but don’t simply throw them in as they are! A stock sound is a means to an end. It’s a raw material from which to craft something new. And it’s always possible to make quick and effective improvements to any sound.

5 Tips!

You’ve trawled through the stock libraries, found a sound for each item on your game’s audio shopping list. Now what? How do you transform something generic and bland into something bespoke and distinctive?

Here are five techniques and tips:

  • Sampling
  • Modulation
  • Filtering
  • Glitching
  • Layering

Important note: always check the usage license of a purchased sound. Most permit their editing and manipulation, provided the sound is not being resold as part of a library. Always check.

Sampling

Sampling is the act of taking a piece of audio and using it as part of a new composition.

As sound designers, you should have some form of sound sampling software or hardware at your disposal. Most samplers allow you to affect the characteristics of the sample, most commonly its pitch, and will map it across a virtual keyboard. The sampler adjusts its playback speed, speeding it up or slowing it down, according to the pressed key’s position (in relation to the sample’s ‘base note’). By experimenting with pitching a sample you can achieve interesting, often unexpected results.

Let’s say the game you’re working on is set in a prehistoric world. Dinosaurs roam the land, the climate is sweltering and the landscape is swampy, with huge insects filling the air. You need sounds for the main dinosaur and the background insects. You’ve tried combining various animal noises to make the main dinosaur’s ‘voice’ but it’s just ended up sounding like a warped, squealing pig. What about pitching down a sample? - Maybe a dog’s bark? Is there any way to re-use it and transform it into an insect call too?

A dog’s bark played three octaves lower transforms it into the main dinosaur sound:

Played three octaves higher transforms it into a strange insect call:

Some samplers can also isolate frequencies within the given sample. These are additional, powerful tools for transforming stock sounds.

Izotope Iris’ spectral re-sampling synthesizer:

Izotope Iris’ spectral re-sampling synthesizer

The yellow waveforms in the image above signify isolated sections in the audio spectrum of the dog’s bark (selected randomly because real life doesn’t follow strict patterns). When pitched several octaves higher than normal, and a with small amount of reverb added, we now have something approaching background insects:

Filtering

The most useful type of filtering in audio manipulation is cutoff filtering using high or low-pass filters. A low-pass filter permits any frequency lower than its setting to pass through unimpeded; higher frequencies are reduced in intensity (attenuated) or removed. High-pass filters work in the opposite manner, allowing higher frequencies to pass through while simultaneously cutting off lower ones.

Say you’re creating distant background ambience. The easiest, most obvious approach is to lower the volume and add reverb to a sound. However, this isn’t quite enough. As a sound source moves away from a listener its higher frequencies are lost; adding a low-pass filter too may give more realistic results.

Another filter trick: strong low-pass filters without reverb can also give the impression of listening to a sound through a wall.

Modulation

Modulation is the effect of altering a value over time. It is particularly useful for augmenting UI sounds or creating sounds with a science fiction flavor.

In synthesizers, LFOs (low frequency oscillators) generate a wave that can alter the pitch, amplitude, waveform, cutoff, filter, mix of separate oscillators, or pretty much whatever the synthesizer allows, of a given signal or tone. Modulating pitch has the effect of creating vibrato; modulating amplitude creates tremolo. A cutoff filter with modulation creates a sweep - where a sound moves through various frequencies (a good example is the quintessential ‘Vangelis sound’ on the Blade Runner soundtrack). As the modulation itself has a waveform, additional effects can be created. For example, a square wave LFO modulating pitch will cause a sample to sound like an alarm, while a sine wave will result in a siren.

These two examples demonstrate how different types of modulation can create different types of sound. The source is a simple, fairly lifeless set of beeps. Applying quick amplitude modulation (tremolo) changes into something that could be used as a UI ‘confirmation’ sound:

By slowing down the tremolo and modulating the pitch too, the same sequence of beeps becomes a sci-fi alarm (when looped):

Glitching

Science fiction, post-apocalyptic and survival horror games often feature instances of glitched sound effects. Broken screens, distorted radio signals, static interference… These sound like complex pieces of audio but can actually be simple to make. There are specialized plugins for glitching audio; however, any basic sound editor software with functions like distortion, pitch-shifting, EQ and compression can be used instead. The only determining factor is the time you’re willing to put into transforming a non-glitched sound into a glitched one.

An example of [heavy-handed] glitched audio:

These were the steps taken:

  1. We started by creating drawn-out ‘freezes’ in the audio, holding on a particular word (it is most noticeable when the narrator says, ‘lasers’). By copying and pasting tenth of a second sections in a short, continuous sequences, we achieved the effect of a broken cassette tape or a needle jumping on a record. Be sure that pasting inserts rather than overwrites.
  2. The next step was to take tiny parts of the audio and distort them into blasts of noise beyond recognition. To simulate the low fidelity of an old radio, a small amount of distortion was also applied to the entire track, causing an underlying hiss.
  3. Small chunks were also pitched up and down to create additional glitches. The effect of a tape winding up or down was achieved by adding a curve to the pitch shift.
  4. Finally, the laser sound was generated by dramatically distorting a section of hiss and then altering its pitch along a bezier curve.

Layering

Sound designers in the film industry construct sound effects by layering numerous sources altered using the techniques we’ve briefly looked at. Ben Burtt famously [spoiler alert] made Star Wars’ TIE fighter fly-by sound by slowing down a car’s skid through a large puddle and layering it over a pitched-down elephant’s roar. Why not follow a similar approach?

When creating the sound effect for the ‘closing doors’ event in our Dino Charge app, our approach was to consider how the internal components of an industrial door might function. This helped establish the sounds we would combine to create a satisfying result. Hydraulic pistons propel the doors to slam shut; gears, motors and chains drive the opening mechanism; the doors are misaligned and scrape the sides. They are heavy and metal so the collision would have both high, metallic tones and a thick bass thud.

In the end, five separate sounds (including the hydraulics of a factory press and the sound of a fire truck ladder extending) were slowed, pitched, layered and edited together to create:

When layering, you should always consider the importance of bass. The most useful kinds to have in your arsenal are rumbles, thuds, and single tones with a variety of waveforms (sawtooth, square, sine). A bass thud or a looped square wave tone can completely change the dynamics and timbre of a sound effect.

For example, simple UI beeps and glitches can be given ‘weight’ by simply adding a bass layer:

Simple as that?

Not quite. There are countless other techniques for manipulating sound; we’ve simply found these five to be the most effective while under time constraints.

We don’t spend enough time on sound but at least it can be time well spent. And 99 cent sounds may end up being great value for money after all.

a Ludomade article

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