From the App Store: Digital Flanger is a simple, convenient flanger effect plugin for Apple Inter-App Audio compatible apps.
On its own, this app does not produce any sound.
Route audio through the Digital Flanger app from any Inter-App Audio Host app (GarageBand, for example) to add a customizable flanger effect.
Digital Flanger Controls:
• Effect In/Out – use the In/Out button to enable or bypass the flanger effect.
• Stereo Level Meters – these lights indicate the stereo audio level in real-time.
• Depth – touch the Depth control knob, then swipe up or down to change the flanger depth.
• Speed – touch the Speed control knob, then swipe up or down to change the flanger speed.
• Clock/Rewind/Play/Record/Host – these buttons reflect and control the audio transport state in the Host app. Tap the Host icon to return to the Host app.