How to get sound effects for your game

There are three ways to get sound effects for a game: take them from a sound library, record them yourself, or generate them from a description. Most games end up using a mix. Whichever you pick, check two things before a sound goes in the build: that its licence covers a commercial game, and that you have a few variations of anything the player will hear over and over, like footsteps or hits.

Sound libraries

A library is the fastest place to start. Free libraries collect sounds uploaded by thousands of people, and paid libraries sell curated packs recorded by professionals.

The catch with free libraries is the licence. Each sound carries its own, and they differ: some are free for anything, some ask you to credit the author in your game, and some rule out commercial use. If you take twenty sounds from a free library, you have twenty licences to keep track of. Write down where each one came from as you add it, because finding out a month before launch is much harder.

Paid packs usually come with one licence for the whole pack, which is simpler. The limit is that everyone else can buy the same pack, so the most popular sounds turn up in a lot of games.

Recording your own

Recording is how you get a sound nobody else has. A phone or a handheld recorder in a quiet room goes a long way: celery snapped for a bone break, a leather jacket shaken for a cloak, a heavy book dropped on carpet for a body fall. Record more takes than you need, a little louder than you think, and cut them into separate files later.

It takes time, and some sounds are hard to record at all. Few people have a sword, a dragon or a spaceship to hand.

Generating them from a description

A sound effect generator makes a sound from a sentence. You describe what it is, where it happens and how it feels, and you get the sound back in a few seconds. It is useful when a library has nothing close, or when you need a specific version of something: footsteps on wet stone in a narrow corridor rather than footsteps in general.

Daydream's game sound effects generator is one. Describe a sound with no music in it, such as "a sword clashing against a metal shield", and you get one take up to 30 seconds long, as an MP3 or a WAV. Every sound is royalty-free for commercial use on every plan, the free one included, so you can ship it in the game, its trailer and its store page. You get 5 free a month, then 5¢ each, from the same credits as songs.

Two things help when writing the description:

• Say what you would hear, not what it is for. "A low growl echoing in a cave" works better than "monster sound".
• Give it a place. The same footsteps sound different on gravel, on wooden stairs and in a stone corridor, and the description is where you choose.

For weather, crowds and the sound of a place rather than single hits, the sound effect generator is set up with ideas for those.

Getting sounds ready for the build

However you get them, a few steps make the difference between a sound that fits and one that sticks out.

• Make variations. Play the same footstep twenty times in a row and the player hears the repetition. Make three to five versions of every sound that repeats, and have the game pick one at random each time, with a small random change in pitch.
• Cut the silence at the start. A sound that starts a few milliseconds late feels slow to a player who just pressed a button. Trim each file so the sound begins on the first sample.
• Match the levels. Sounds from different sources come in at different volumes. Bring them to a similar loudness before you start mixing in the engine, or you will spend the mix fighting the files.
• Use WAV in the project. Keep the uncompressed file in your project and let the engine compress it for each platform when it builds.
• Mono for sounds that move. A sound attached to something in the world, like an enemy's footsteps, is usually best as a mono file so the engine can place it in space. Keep stereo for ambience and interface sounds.
• Loop ambience with a crossfade. A single take of rain or wind will click if you loop it end to start. Loop it in the engine with a short crossfade, or layer two takes offset from each other.

Sound effects and music together

Sound effects sit on top of the music, so it helps to plan them together. A busy combat track leaves little room for sword hits, and a quiet exploration theme leaves plenty. If you are making both, it is easier to hear how they sit when they come from one place: the same generator makes music for every scene in a game, from a dungeon theme to a boss fight, with each song's stems so you can drop a part when the action gets loud. There is also a free game music pack to start from.

For a wider look at choosing a music tool for a game, see the best AI music generator for video games.

Questions

Can I use free sound effects in a commercial game? Only if each sound's licence allows it. Free libraries mix licences: some sounds are free for any use, some need a credit, and some exclude commercial use. Check each one and keep a list.

What format should game sound effects be in? WAV in your project, so nothing is lost before the engine compresses it for each platform. Use mono for sounds placed in the game world and stereo for ambience and menus.

How many variations of a sound do I need? For anything the player hears often, like footsteps, hits and pickups, three to five, played at random with a small change in pitch. One-off sounds, like a door that opens once, need only one.

Are Daydream's sound effects free to use in a game I sell? Yes. Every sound is royalty-free for commercial use on every plan, Free included. You get 5 free a month, then 5¢ each, from the same credits as songs.