GarageBand ‘11: Import an audio file
You can import audio files of the following file types into a GarageBand project:
AAC (except protected AAC files)
To import an audio file:
Drag the audio file you want to import from the Finder into the timeline, to the empty area below the existing tracks.
A new Real Instrument track is created, and the audio file appears as an orange region in the track.
Imported audio files should have a sample rate of 44.1 kilohertz (kHz) and a bit depth of 16 bits. Files with a different sample rate might play back faster or slower (for example, files with a sample rate of 48 kHz, a common format for camcorders, will play back faster). You can convert files to 44.1 kHz using QuickTime Pro or another application before importing them into GarageBand.
Audio files you import from the Finder do not change to match the tempo or key of your project. Compressed audio files you import into a project remain compressed, saving space and time.