Why does your stomach growl?
Dear Straight Dope:
My husband and I were watching TV last night, and our stomachs were playing "dueling gurgles." This got us wondering why stomachs make noises. Also, what causes them to growl when we are hungry?
Well, not to be indelicate here, but it's the shifting of matter, acids, and gases--oh, hell, let's be indelicate. Mostly, it's the passage of gas downward through your system. If your stomach is making a lot of noise, you can pretty much bet that before long, you're going to do something that makes the indelicacy of this answer seem rather polite. There's even a medical term for this: borborygmus.
Some of the noise can also simply be a result of the digestion process at work, and the reason our stomachs growl more when we're hungry is just that there's more empty space involved.