Overdubbing occurs when you record directly over a part of a song, replacing the instrument part with a new part. With GarageBand in iLife '11, you overdub by creating a cycle region, which restricts the recording to a specific time segment in the selected track.

You can record a performance into a cycle region of a track of the same type (Real Instrument recording into a Real Instrument track, Electric Guitar recording into an Electric Guitar track, or Software Instrument recording into a Software Instrument track).

Each recording in a cycle region is normally stored as a separate take, but you can also use a cycle region to merge multiple recorded takes with a Software Instrument to layer the sound (such as multiple drum beats) without having to resort to using multiple tracks. To change the way the cycle region works, choose GarageBand→Preferences, click the General tab, and turn on the option labeled Cycle Recording: Automatically Merge Software Instrument Recordings.

To create a cycle region, follow these steps:

  1. Click the Cycle button.

    The Cycle button, with its revolving arrows, is in the row of transport control buttons. This button opens the cycle ruler, which is a tiny second ruler that appears below the beat ruler.

  2. Drag inside the cycle ruler to define a yellow bar that indicates a cycle region in the timeline.

    Make sure that the beginning and end of the yellow bar are set accurately in the timeline for the time section.

  3. Select a track and click the Record button to record a performance.

    With the cycle region defined, you record directly into the cycle region of that track. As you record, the region changes to show a badge showing the number of takes (unless you switched the preferences option to merge recordings). You don’t have to click to stop and record again — the cycle region loops automatically.

  4. When you finish recording, click the Cycle button to turn off the cycle region.

    After recording multiple takes, you can select different takes or delete takes by clicking the number badge in the recorded region. If you switched the preferences option to merge recordings, you end up with one recording of all merged performances.