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# Audio Unit Scopes

Programmatic roles and contexts for audio unit properties.

## Topics

### Constants

[`var kAudioUnitScope_Global: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Global)

[`var kAudioUnitScope_Group: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Group)

In macOS, a context specific to the control scope of audio unit parameters.

[`var kAudioUnitScope_Input: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Input)

The context for audio data coming into an audio unit.

[`var kAudioUnitScope_Layer: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Layer)

[`var kAudioUnitScope_LayerItem: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_LayerItem)

[`var kAudioUnitScope_Note: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Note)

In macOS, a scope for changes to an individual musical note. The element identifier used with this scope is the unique note identifier returned from a started note (see the `MusicDeviceStartNote` function in `AudioUnit/MusicDevice.h`).

[`var kAudioUnitScope_Output: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Output)

The context for audio data leaving an audio unit.

[`var kAudioUnitScope_Part: AudioUnitScope`](/documentation/AudioToolbox/kAudioUnitScope_Part)


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