I suppose this is not something you can find a technical quote for. In fact I kind of hope it isn't.

What does it actually sound like inside, let's say, Destiny?

No decibel levels allowed! Does it sound like a large office? Inside a car on the interstate? Waiting at the tracks while a train goes by (windows open/windows closed)? Starship Voyager? In front of an air conditioner? In bed with earplugs in? By a white noise sleep machine? ???

Somebody ask Peggy!