It could be many things, so you should ask your doctor. Because you mentioned an "empty hunger" and also because you mentioned you didn't like to sit near others because of this noise, I have an idea that it could possibly be caused by anxiety. Also, you could have irritable bowel syndrome (read up on that). Many times, especially in women, IBS flares up when our anxiety level increases. Also, when some people have an anxiety/depression situation, they tend to feel that sort of strange hunger, even though they have already eaten. Just a thought, but you should speak to your doctor if this is a constant problem.