How do I get music in Unity?

ByJael Lawler

Unity is a popular game engine used to develop video games and other interactive 2D and 3D content like architectural visualizations or animated films. As with any multimedia application, audio is a critical component of the user experience in games developed with Unity. Game engines like Unity provide a framework and tools to help developers integrate audio into their games.

Audio adds immeasurable depth and emotion to games. Music sets the mood and ambiance while sound effects provide sensory feedback for player actions. Rich, layered audio draws players into the game world and makes it feel alive. Without any audio, games feel sterile and hollow.

This article will provide an overview of Unity’s built-in audio features and how to get started importing, playing, and optimizing audio clips in your Unity projects. We’ll look at topics like background music, ambient sounds, volume control, audio effects, and more. By the end, you’ll have a solid grounding in working with audio so you can create immersive sonic experiences in your Unity games.

Unity’s Audio Features

Unity comes with a built-in audio engine that provides a range of features for working with audio in your games and applications. Some of the key audio features in Unity include:

Built-in Audio Engine: Unity has a full digital signal processing (DSP) audio engine built directly into the Unity editor. This allows you to play back, mix, and apply effects to sounds and music directly inside of Unity without needing any external tools or plugins.

Audio Clips: You can import audio files (WAV, MP3, OGG etc.) into Unity as AudioClips. These can then be configured and controlled via code to play sound effects, background music, ambient loops and more. Audio clips allow precise control over playback, looping, scheduling and effects.

Audio Mixer: The mixer allows you to control audio levels, apply effects, route audio and mix multiple sounds together. You can have multiple mixers if needed for different in-game scenarios. The mixer provides volume, EQ, dynamics control and more.

Audio Effects: Unity comes with a range of built-in audio effects that you can apply to your sounds. These include spatial effects like reverb and 3D positioning, as well as common effects like chorus, distortion, low pass filters and more. Custom audio effects can also be created with scripts.

For more details, refer to the Unity Manual on Audio https://docs.unity3d.com/2022.2/Documentation/Manual/Audio.html

Importing Audio Files

Unity supports importing audio in common formats like WAV, MP3, OGG and AIFF. To import an audio file into your Unity project, simply drag the file from your file browser into the Project window in the Unity editor. Unity will automatically convert the audio into its own Unity-specific format while importing.

When an audio file is imported, Unity will generate an AudioClip file that contains the compressed audio data. The AudioClip is the component that actually holds the audio data and controls playback in Unity. It gets attached to audio sources like the AudioSource component in order to play sounds in the game.

By default, Unity will compress audio during import to optimize file size while maintaining quality. You can adjust audio import settings like compression, load type (compressed/decompressed) and more on the Audio tab in the Import Settings window.

Playing Audio Clips

The AudioSource component is used to play back audio clips in Unity. To play an audio clip, it first needs to be assigned to the Audio Clip property on the AudioSource component. Then, calling the Play() method will start playback of the clip.

There are a few key properties on AudioSource that control playback:

  • loop – Whether the clip should loop back to the start when it reaches the end
  • spatialBlend – Controls how much the audio is spatialized between stereo and 3D spatial sound
  • playOnAwake – Whether the clip should start playing immediately on scene load

Setting spatialBlend to 1 enables full 3D spatial sound, which attenuates the sound based on its 3D position and distance from the listener. This allows sounds to be localized and heard realistically from different parts of the game world.

The Play() method also has some optional parameters like startTime to begin playback midway through a clip, and loop to override the default loop property.

So in summary, attaching an AudioSource + Audio Clip allows powerful control over audio playback in Unity games.

Adjusting Volume

The volume of audio clips and sources in Unity can be adjusted in several ways. The most basic way is through the AudioSource.volume property which controls the volume of an individual audio source or clip. This value ranges from 0 to 1, with 1 being full volume.

For greater control over volumes, the Unity Audio Mixer allows you to control volumes across groups of sounds and adjust volumes logarithmically. This is useful for creating master volume controls and audio sliders. Within the Audio Mixer, you can right click on a Mixer Group’s volume parameter to enable a slider control for it.

Volume properties should be adjusted with care, as setting volumes too high can cause clipping and distortion. It’s generally best to keep volumes at reasonable levels and make adjustments through the Audio Mixer for consistency across sounds.

Adding Effects

Unity provides several built-in audio effects that can be added to audio sources to modify their output. These effects include reverb, echo, and 3D spatialization effects.

The most common way to add audio effects is via the Audio Filter component. This can be added to any AudioSource object. The Audio Filter exposes parameters for controlling effects like low pass, high pass, echo, and reverb.

For example, adding the Reverb Filter creates a reverberant sound, similar to being in a large hall or cavern. Adjusting parameters like Room Size and Dampening Frequency modifies the reverb characteristics.

The Audio Filter component provides a quick and easy way to enhance audio clips in your Unity project. Multiple filters can be added to a single AudioSource for layering effects.

Background Music

To play persistent background music that continues between scenes in Unity, you’ll want to use a special script component called Don’t Destroy On Load. This allows your background music game object to persist when loading new scenes.

First, create an empty game object and add an Audio Source component to it. Set the AudioClip you want for your background music. Make sure Loop is checked so it repeats continuously.

Then add a Don’t Destroy On Load script component. This simple script tells Unity not to destroy this game object when loading a new scene.

With this set up, your background music will continue playing uninterrupted as players transition between different scenes. Just be sure to load the scene with the music game object first.

For more details and examples, check out this Unity forum thread: Playing background music.

Ambient Sounds

Ambient sounds help add realism and immersion to a Unity scene. These are background sounds like birds chirping, wind blowing, crowds murmuring etc. Unity provides several ways to add ambient sounds:

You can simply drag an ambient sound clip onto an empty GameObject. This will play the sound continuously at the location of that GameObject. Adjust the Audio Source components to control volume, pitch etc.

For more dynamic ambient sounds, you can use scripts to randomly trigger sounds. For example, this script from the Unity forums randomly plays bird chirps clipped from Audio Controller asset:

if(Random.value < 0.001f){
   AudioSource.PlayClipAtPoint(birdChirpClips[Random.Range(0, birdChirpClips.Length)], transform.position);
}

You can attach this script to multiple GameObjects scattered around the scene. The random logic will give the impression of random birds chirping.

For large environments like forests, randomly triggering many sounds from different objects can be taxing. Instead, you can simply play long ambient loops of forest sounds from a few GameObjects.

Adjusting parameters like volume and pitch randomly via script makes loops sound more dynamic. You can fade sounds in and out for a realistic experience. Environments in games like The Legend of Zelda: Breath of the Wild use these techniques to great effect.

Advanced Audio

Unity provides several advanced audio features to help create immersive 3D environments. These include 3D spatial sound, occlusion effects, and reverb zones.

Unity's audio system supports 3D spatial sound, which allows sounds to dynamically change based on their position and distance relative to the listener. To enable 3D audio, audio sources need to be configured with an Audio Source component. The 3D spatializer plugin then handles modifying the sound based on the source's position and the listener's position. This creates a realistic sense of audio moving through space as objects and the player move.

Another key advanced feature is audio occlusion, which simulates how sounds are muffled or blocked by objects in the environment. Occlusion effects occur when there is an object between the audio source and the listener. Unity provides occlusion plugins that can model how walls, barriers, and other objects would dampen and filter sounds in the real world.

In addition, reverb zones can be added to rooms or areas to simulate environmental acoustics. Reverb zones apply audio effects like reverberation tail to any sounds playing within their trigger volume. This provides each space with its own acoustic signature. Reverb zones combined with occlusion allow for incredibly realistic ambient audio that responds dynamically to the environment.

These advanced spatial audio features enable game developers to create deeply immersive audio worlds in Unity. With full control over 3D spatialization, occlusion, and environmental effects, developers can craft audio experiences that surround and engage players.

Sources:

[Advanced Audio Manager - Sound FX](https://assetstore.unity.com/packages/audio/sound-fx/advanced-audio-manager-179699)

[Advanced sound playing](https://forum.unity.com/threads/advanced-sound-playing.29343/)

Optimizing Audio

Optimizing audio in Unity involves techniques to reduce file size, ensure efficient loading, and minimize performance issues. Here are some key optimization strategies:

Compression

Using compression can significantly reduce the file size of audio clips. Unity supports compressed formats like MP3, OGG, and ADPCM. Compressed clips take up less space and load faster while retaining good quality.

Reducing File Size

In addition to compression, further file size reductions can be achieved by:

  • Lowering bitrate and sample rate if quality is not compromised
  • Trimming silence/unused parts of audio clips
  • Converting stereo clips to mono if positional audio is not required

Loading Strategically

Large audio files can be demanding to load at runtime. Strategies to optimize loading include:

  • Stream long background music clips instead of loading them fully upfront
  • Preload common sound effects that are used repeatedly
  • Load infrequently used clips only when needed

With the right optimization techniques, Unity's audio system can deliver high quality sound without performance issues.

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