The music tempo change glitch is a glitch that occurs in Sonic the Hedgehog 2 for the Sega Mega Drive/Genesis. The sound driver fails to load the proper speed for certain songs if the tempo is changed while the 1up jingle is playing or the level music is fading in. There are two different ways to execute this glitch, with the first procedure being the easiest and fastest way.
- The player must enter the options screen.
- The player must play a song, then play the one up jingle. Quickly before the jingle is done playing the player must select either $7B or $7C in the sound test.
- The player must gain an extra life.
- The player must quickly have access to a Speed Shoes monitor and needs the power up before the level music fades back in.
$7B in the sound test speeds up the music, while $7C reverts it back to normal speed. Not all songs will be effected, and some songs slow down while others play too fast.