It seems like a book that would have a small cult following. I'm about halfway and so far, so weird.
White noise is sort of a background non-noise, usually meant to cover up other distractions.
Third shift workers use it to block out outside sounds so that they can sleep at off hours and parents can buy tapes of it to play in the nursery to supposedly lull baby to sleep. As for how it pertains to the theme of DeLillo's novel, at halfway through, I can only guess, so I won't. I'm hoping that I will figure it out by the end. So far, it's definitely not my cup of tea. I'm getting deja vu all over again of a Lit class in college in which I was subjected to Joyce's Ulysses.