Inter-App Audio (IAA) is a technology developed by Apple Inc and designed to route audio and MIDI signals between various applications within devices based on the iOS mobile operating system.

Inter-App Audio allows audio apps that are instruments, effects, or generators to publish an output object which can be used by other audio apps. An app that publishes an output is called a node. An app that connects and uses one or more nodes is called a host.

Node applications can be of the following types:

  • Host  (can receive MIDI audio signals and produce audio signals)
  • Instruments (produce MIDI audio signals)
  • Effects (can receive, transform and send back audio signals)

In a few words Inter-App Audio (IAA) allows the connection of audio applications with other audio applications, as long as they include this feature integrated into the application.

iDousyn is an instrument that sends midi audio signals to all HOST applications.