To resolve the issue, press the Home button. Then, tap the GarageBand icon to reopen the app.
GarageBand for iOS: Microphone not recognized with iPod touch (3rd generation)
If you connect an microphone such as the iPhone Stereo Headset, Apple Earphones with Remote and Mic, IK Multimedia iRig, or Blue Mikey while GarageBand for iOS is running, the microphone may not be recognized. This occurs with iPod touch (3rd generation).
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