[emotiveengine]

I spent a while trying to sync animation to music and the biggest surprise was how much rhythm alone does. Change BPM, same notes, same key, and the emotional feel completely flips. 120 BPM is neutral. 60 is contemplative. 160 is anxious. Nothing else changed.

If you strip a song down to just its rhythm, no pitch, no timbre, people can still tell you what emotion it's going for. Add the pitch back and it barely moves the needle. Timing between events does most of the heavy lifting. The actual "sound" part is almost window dressing on a temporal skeleton.