I once had it happen during a job interview. We all pretended we hadn't heard anything, and they probably assumed I was hungry. I got the job. My pouch was less than a year old at the time. Things are much quieter now, 13 years later.

I would get it more often in the beginning when I had strictures; after I got them dilated the sounds went away (mostly).  But sometimes it felt like a freight train going through my small intestine and making a bunch of noise.

The most likely culprit is adhesions.  I have these and my gut can be quite loud at times. She's a beast. Unfortunately, there isn't much you can do to prevent this.

I get this too.  I feel like it is trapped gas in  my small intestine finally finding a way to be released.  I'm sure I am full of adhesions and it takes some acrobatics on behalf of my intestine to become unkinked.  I always smile (inwardly) when this happens because it means my intestines are working the way they should and all is right with the world.

For me, an empty stomach is the culprit.  If I keep some food in me the rumbling is minimal.

Was much noisier in the beginning. Now, 24 years post op, its pretty normal unless I get past the comfort stage of needing to go, then things can get noisier. Bet you'll notice this change over the years, too. 

Yes I do have a few cramps which are painful enough to stop me walking if I am, they are followed by some noisy movements in the pouch. This happens usually when I am delaying going to the loo if needed and feel much better with no cramps once gone.I had my op 15 years ago and not have had any problems with adhesions yet!!