While at the title screen, press and hold START + A to open the sound test mode.

LEVEL PASSWORDS

Level 1 - 2 : MDRR
Level 2 - 1 : NMLL
Level 2 - 2 : NWKL
Level 3 - 1 : LGZQ
Level 3 - 2 : GPTW
Level 4 - 1 : GNXF
Level 4 - 2 : KHCN
Level 5 - 1 : QGVN
Level 5 - 2 : WBZT
Level 6 - 1 : FFHG
Level 6 - 2 : CKQG
Level 7 - 1 : GPZT