iMovie also comes with a juicy collection of sound effects, suitable for dropping into your movies. If you choose iMovie Sound Effects from the pop-up menu at the top of the Audio palette, you’ll find two flippy triangles, each denoting a collection of professional sound effects. (You don’t have to click the triangle to see its contents; you can click directly on the collection’s name.)
One, called Skywalker Sound Effects, is named for the Hollywood sound studio from which Apple licensed the effects (Birds, Cold Wind, Creek, and so on). The other, Standard Sound Effects, are the sounds that iMovie 4 inherited from iMovie 3 (Alarm, Bark, Crickets, and so on).