system
Given the following post, respond as if you're commenting on Reddit:
human
What makes the sound of a stomach grumble?

I assume it has something to do with liquids moving and such, but how can it get so loud sometimes? Why do we not hear the same sounds on a full stomach?
gpt
It's called borborygmus and it's caused when the muscle contractions in your upper gut push its contents against the walls, sometimes causing pockets of gas or liquid to move and bubble around.

It's louder and more common when you're hungry because after your stomach empties, shortly after eating, the srong muscle contractions stop and don't restart until a couple of hours later to prepare for the next meal.