Heal Signs:
Destroy a sign and then play C-Left, C-Right, C-Down with the Ocarina.

Travel Forward in time 12 Hours:
Play C-Right, C-Right, A, A, C-Down, C-Down with the Ocarina.

Slow Time (Normal Movement):
Play C-Down, A, C-Right, C-Down, A, C-Right with the Ocarina. To return to normal just repeat the song.