It is the weirdest disposal I've ever seen.  The noise it makes sounds like gears shifting in a car, even when there is nothing in it.  I can't tell from listening to it if it has "chewed up" anything that I've put in it, so eventually I simply shut it off and  hope it's doing its job.  I am 70 and sincerely doubt I'll ever get my husband to install another one, so it had better work!