Does the music ever affect sound design? Do you ever do one thing and then, when you hear the music the procedural system is going to play, decide you want something more in line with that? Does the tail wag the dog?

You've got two different types of music. You've got diegetic and non-diegetic. So diegetic is music that is in the location, like a radio or PA system and stuff like that. So that will be affected by propagation, all that kind of stuff. You shoot a speaker, it'll be destroyed and stuff. But then you've got the score, which is kind of god music, non-diegetic. Now, one wouldn't really cause another one to trigger necessarily, but music dynamically switches based on the intensity, all that kind of stuff. The main way they interact is probably more with the mix. So what you can do is dynamically meter the frequency spectrum of the sound effects. And if you deem the sound effects to be more important, you can bring down those frequencies in the music. So you're kind of carving out frequencies in the music to allow the sound design to poke through. Or conversely, you can have it the other way around. So if you have certain frequencies in the music you want to emphasize, you can bring down the sound effects to accommodate that.

We also have to be careful about overly tonal sound design as well sometimes. If there's the cinematic music for coming down to a certain planet, and you happen to do the background planetary ambience for that planet with a slight tonal element that is half a step below the key of the music...

Or less than half a step.

That might sound a bit funky.