Baldi’s Basics uses MIDI music, but the creator of the game converted all the music to WAV files. I was able to re-create them all, so they’re exactly the same, but reverted to MIDI again.

Downloads:
MIDI files –
Soundfont –

Programs used:
Video editor – Adobe Premiere Pro
MIDI creator – Aria Maestosa
Speaker recorder – Audacity
Screen recorder – Fraps
MIDI player – Synthesia