---
title: PHASESoundEvent
framework: phase
role: symbol
role_heading: Class
path: phase/phasesoundevent
---

# PHASESoundEvent

An object that determines which audio to play.

## Declaration

```swift
class PHASESoundEvent
```

## Mentioned in

Playing sound from a location in a 3D scene

## Overview

Overview A sound event represents a logic tree, or hierarchy, that defines what, when, and how the framework plays a sound at runtime. You configure the tree with conditions based on your app’s state. When you invoke a sound event’s root node at runtime, the framework navigates the tree by branching based on the logic, landing on a playable node that sends the right audio to the output device: To invoke a specific one-time sound, create a sound event from a single sampler node. To invoke a sound event that tailors its sound based on your app’s state, define a sound event hierarchy containing one or more control nodes; see Sound Event Nodes. For example, to play either footsteps or a jumping noise depending on the hero’s state, you configure a switch node that navigates based on the hero’s hypothetical isJumping metaparameter. For sound event nodes that play audio, the asset’s playbackMode determines whether the audio loops. One-time sound events stop automatically at the end of the audio data. Looping sound events (those with playbackMode = PHASEPlaybackMode.looping) require you to explicitly call stopAndInvalidate() to stop the audio. Playing a one-shot channel-based sound Apps create a sound event by requesting one from a sound event node asset. To create a sound event node asset, combine a sound asset (the source audio data) with a mixer object (which combines sound layers for output) to create a node, and add the node to the asset registry. By creating a sound event from a sampler node (PHASESamplerNodeDefinition), the following code plays an audio file once before discarding it. // Create a channel layout for audio types that contain no channel metadata.  let stereoLayout = AVAudioChannelLayout(layoutTag: kAudioChannelLayoutTag_Stereo)

// Load an audio file from the bundle. let bangSoundURL = Bundle.main.url(forResource: "bangSound", withExtension: "wav")!

// Create and register a sound asset. var bangSoundAsset:PHASESoundAsset! do {      bangSoundAsset = try engine.assetRegistry.registerSoundAsset(         url: bangSoundURL,          identifier: "bangSound",          assetType: .resident,          channelLayout: stereoLayout,         normalizationMode: .dynamic) } catch { print("Failed to register the sound asset.") }

// Create a mixer that routes sound directly to the output. let stereoMixer = PHASEChannelMixerDefinition(channelLayout:stereoLayout!)

// Create a sound event node. let bangSoundSamplerNode = PHASESamplerNodeDefinition(     soundAssetIdentifier: bangSoundAsset.identifier,      mixerDefinition: stereoMixer, identifier:"bangSoundNode")

// Add the sound event node to the asset registry and retrieve the asset object. var bangSoundSoundEventAsset: PHASESoundEventNodeAsset!  do {     bangSoundEventAsset = try engine.assetRegistry.registerSoundEventAsset(         rootNode: bangSoundSamplerNode, identifier:"bangSoundTree") } catch { print ("Failed to register the sound event node.") } The resulting node asset represents a template for audio that’s ready for playback. To play the audio, spawn a sound event off of the node asset and call start(completion:) to invoke the sound event. // Create a playable sound event from the template sound event asset. var bangSoundEvent: PHASESoundEvent! do {         bangSoundEvent = try PHASESoundEvent(engine:engine,          assetIdentifier: bangSoundEventAsset.identifier) } catch { print ("Failed to create the sound event.") }

// Play the one-shot sound event. bangSoundEvent.start() important: To play the same sound asset again, create another sound event object. After the first start(completion:) call on a particular PHASESoundEvent instance, subsequent calls have no effect.

## Topics

### Creating a Sound Event

- [init(engine:assetIdentifier:)](phase/phasesoundevent/init(engine:assetidentifier:).md)
- [init(engine:assetIdentifier:mixerParameters:)](phase/phasesoundevent/init(engine:assetidentifier:mixerparameters:).md)

### Configuring Mixers and Metaparameters

- [mixers](phase/phasesoundevent/mixers.md)
- [metaParameters](phase/phasesoundevent/metaparameters.md)

### Preparing Playback

- [prepare(completion:)](phase/phasesoundevent/prepare(completion:).md)
- [PHASESoundEvent.PrepareHandlerReason](phase/phasesoundevent/preparehandlerreason.md)
- [prepareState](phase/phasesoundevent/preparestate-swift.property.md)
- [PHASESoundEvent.PrepareState](phase/phasesoundevent/preparestate-swift.enum.md)

### Checking Playback Status

- [renderingState](phase/phasesoundevent/renderingstate-swift.property.md)
- [PHASESoundEvent.RenderingState](phase/phasesoundevent/renderingstate-swift.enum.md)

### Providing Buffered Data

- [pushStreamNodes](phase/phasesoundevent/pushstreamnodes.md)

### Starting Playback

- [start(completion:)](phase/phasesoundevent/start(completion:).md)
- [PHASESoundEvent.StartHandlerReason](phase/phasesoundevent/starthandlerreason.md)

### Seeking a Time

- [seek(to:completion:)](phase/phasesoundevent/seek(to:completion:).md)
- [PHASESoundEvent.SeekHandlerReason](phase/phasesoundevent/seekhandlerreason.md)

### Pausing Playback

- [pause()](phase/phasesoundevent/pause().md)
- [resume()](phase/phasesoundevent/resume().md)

### Stopping Playback

- [stopAndInvalidate()](phase/phasesoundevent/stopandinvalidate().md)
- [isIndefinite](phase/phasesoundevent/isindefinite.md)

### Instance Properties

- [pullStreamNodes](phase/phasesoundevent/pullstreamnodes.md)

### Instance Methods

- [resume(at:)](phase/phasesoundevent/resume(at:).md)
- [seek(to:resumeAt:completion:)](phase/phasesoundevent/seek(to:resumeat:completion:).md)
- [start(at:completion:)](phase/phasesoundevent/start(at:completion:).md)

## Relationships

### Inherits From

- [NSObject](objectivec/nsobject-swift.class.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Audio Selection and Playback

- [PHASESoundAsset](phase/phasesoundasset.md)
- [PHASESoundEvent.RenderingState](phase/phasesoundevent/renderingstate-swift.enum.md)
- [PHASESoundEventNodeDefinition](phase/phasesoundeventnodedefinition.md)
- [PHASESoundEventNodeAsset](phase/phasesoundeventnodeasset.md)
- [PHASEAsset](phase/phaseasset.md)
- [Sound Event Nodes](phase/sound-event-nodes.md)