If you used to make podcasts or sound effects with old versions of GarageBand, you might remember the "Podcasts" category of sound loops. It contained a lot of funny jingles, nice ambient sounds and numerous sound effects that were quite useful.
Those loops were in fact part of the iLife Sound Effects library, shared between iMovie, iPhoto, and GarageBand. But since Apple discontinued the iLife all-in-one package and started distributing separated apps on the Mac App Store, those loops are not installed anymore.
That is, if you had a previous version of the iLife apps installed, the loops are still present and will be loaded by GarageBand. But if you do a clean system install or switch to a new computer, they won't be available.
Fortunately, those sounds still exist! They are used by the iMovie presets, and are thus stored in the iMovie application package. Namely, in
iMovie.app/Contents/Resources/iLife Sound Effects and in
iMovie.app/Contents/Resources/iMovie Sound Effects. You can copy them to a safe place and import them in GarageBand by drag-and-dropping them in the Loops panel.
An important note: GarageBand will only import .caf files, but the files in the iMovie Sound Effects folder are in .mp3. You can convert them using online utilities or via the command-line, using the
afconvert tool and the command
afconvert -f caff -d LEI16@2205 path/to/file.mp3
This will generate the .caf file in the same directory. To run the conversion for all sound files in the directory, create an Automator action with:
a "Run Shell Script" block, passing input as arguments, with the script
for f in "$@"
afconvert -f caff -d LEI16@2205 "$f"
Also, GarageBand filters the loops based on the tone of the opened project. This can be disabled in GarageBand → Preferences → Loops, uncheck Filter for more relevant results.