<!--
{
  "documentType" : "article",
  "framework" : "AudioToolbox",
  "identifier" : "/documentation/AudioToolbox/1584139-input_output_audio_unit_subtypes",
  "metadataVersion" : "0.1.0",
  "role" : "collectionGroup",
  "title" : "Input/Output Audio Unit Subtypes"
}
-->

# Input/Output Audio Unit Subtypes

Input/output audio unit subtypes for audio units provided by Apple.

## Topics

### Constants

[`var kAudioUnitSubType_GenericOutput: UInt32`](/documentation/AudioToolbox/kAudioUnitSubType_GenericOutput)

[`var kAudioUnitSubType_VoiceProcessingIO: UInt32`](/documentation/AudioToolbox/kAudioUnitSubType_VoiceProcessingIO)

An audio unit that interfaces to the audio inputs and outputs of iOS devices and provides voice processing features.


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)