Karaoke Revolution

You need 90% matched pitch to get the Platinum Skill Prize, and you need to do that 90 times total.  If you haven't obtained enough platinums skill prizes between career mode, "Eclectic Dreams", "The Platinum 5" and all your attempts at "Hard Carbon", you will need to get a few more now.

From the Main Menu select "Options", "Extras", "High Scores" to see the highest scores. Look to see what song you have been scoring the highest % on (NOT SCORE). You should be able to keep singing that one song over and over, and you can even do it on Easy difficulty in 'short' mode.

From the Main Menu select "Options", "Extras", "Statistics" to see your current progress.
NOTE: Singing a full 5 song set will only count as ONE skill prize, not five.