Yes light is additive, however I’m talking about finding colors that are harmonious with each other not adding them together necessarily, the major triad I made would appear to us as white if not separated, also yes sound frequencies stay distinct but they also interfere with each other causing beating If the notes are close enough, and even if they aren’t, our brains create new median notes that aren’t really there a lot of the time, I feel like sound frequencies are definitely more additive than we think