I don't chew gum (because I complain about public, smacking gum-chewers who search and destroy that tiny little air pocket of POW!, and that would be hypocritical of me, wouldn't it?). I tried to think if I was even the littlest bit annoying, and have to say that I am not. I only hum. Humming is harmless and fun, and who would ever call someone out for humming? Hmm hmm hmm...and deeper, hum hum...See, not irritating at all.
I hum when I write.
I hum when I clean up after the cat. It seems to help keep my own throat from opening up and sharing.
I even hummed during my sigmoidoscopy and lest you think I share too much, the doctor told me, and I quote, "keep on doing what you're doing." Hmm hmm hmmm. So there.