Input monitoring lets you hear a live microphone or instrument through GarageBand while preparing or recording a part. If that sound leaves through speakers and reaches the microphone again, it can produce feedback. Arrange the listening route before enabling the live return.

Use headphones for a microphone recording session and start at a comfortable low listening level. If feedback occurs, turn monitoring off rather than raising or repeatedly testing the speaker volume. Keep the microphone position and selected input unchanged while diagnosing the route.

Use the track’s monitoring control

In GarageBand on Mac, the Monitoring button in an audio track header turns its live input return on or off. With it on, you can hear the input alongside the project while practising or setting levels. Turn it off when the live return is no longer needed.

Apple specifically warns that speaker output can be picked up again and recommends headphones to help avoid feedback. A headset’s separate sidetone setting is a different control; changing that setting does not establish whether GarageBand is monitoring the selected track.

Apple also documents a safeguard: selecting the built-in microphone as the input in GarageBand’s Audio/MIDI settings turns monitoring off for Electric Guitar tracks to avoid unwanted noise. If a monitor state changes after selecting that input, check this documented behaviour before assuming the track is damaged.

Separate live listening from recorded playback

Speak or play briefly and confirm that the intended track is the one being heard. Then make a short recording and listen back with live monitoring off. Hearing yourself live is not evidence that the desired passage was successfully recorded.

Listen for unwanted room sound, a competing live return or distortion. If the recorded result is good but live listening remains distracting, investigate the monitoring route without changing several recording settings at once.

Before leaving the session, turn off unnecessary monitored tracks. Recheck the route when switching between headphones and speakers so a safe recording arrangement does not become a feedback loop at the next playback.

References: Apple: GarageBand input monitoring.