Black Panels: During gameplay press R3, L3, R3, R3, L3, R3, L3, L3, R3. When you begin a new game, you'll see black panels. 
Blurry Mode: During gameplay press R3, R3, R3, R3, L3, L3, L3, L3, R3 to turn everything blurry 

Transparent Panels: During gameplay press L3, R3, L3, L3, R3, L3, R3, R3, L3. When you beging a new game, you'll see transparent panels 

Tunnel Mode: During gameplay press L3, L3, L3, R3, R3, R3, L3, R3, L3 to see things a little differently. Repeat the code for another new view 

Turn Notes into Monkey Heads: To turn the note gems into monkey heads, L3, L3, L3, L3, R3, R3, R3, R3, L3 during gameplay 

Unlock Freq Parts and Prefabs: Beat the boss song of any level to unlock extra Freq pieces. In addition, you can finish the Bonus Song on each level to gain new Freq parts and Prefabs. 

Scramble gem positions: X + X + Left + Left + R3 + R3 + Right + Right 

Graphics FX 1 - Monkey Gems: L3 + L3 + L3 + L3 + R3 + R3 + R3 + R3 + L3.