Backmasked audio reveals a familiar tune.
Time-reversing the music from the latest The Legend of Zelda: Skyward Sword trailer reveals that the track is based on Zelda's Lullaby, a recurring theme that originated in A Link to the Past.
Youtube user FPawesome1 first discovered the hidden motif after playing a recording of the trailer backwards. The trailer was shown by Satoru Iwata at his GDC keynote. Below, you can watch the original trailer, followed by a time-reversed version.
Nintendo is known for hiding musical "easter eggs," such as the GameCube menu music, which was a slowed-down version of the Famicom Disk System boot jingle.