It happens with little notice. You have a good meal, a nice wine, and you sit back ready to continue a good conversation. Suddenly, there's a feeling of pressure deep inside your belly and next a gurgling, burbling noise that raises both your eyebrows and that of your dinner guest. This doesn't mean you are suffering an intestinal problem. Believe it not, most likely everything is just normal in your stomach.
The concept of noise emanating from the stomach is a bit of a misnomer. Technically speaking, the noise is really coming from your intestines, but because people traditionally think the stomach is near the belly the intestinal noise gets attributed.
Stomach noise is created by digestion. This process occurs as stomach acids--corrosive liquids created in the stomach--travel through the intestines digesting food and breaking it down for absorption by the body. Stomach noise can happen before, during and after a meal as a result. Abdominal noise occurs as food is moved. Gas is displaced, empty areas between the intestines fill up and liquid is displaced. All of this motion creates sounds.
Noise in the Empty System
Even when there is no food, noise is created by the intestines. The intestinal tubes are hollow, so as acid liquid moves through it will gurgle similar to water moving through half-filled plumbing pipes in a building. Usually this is harmless body behaviour and nothing to worry about (aside from being a bit embarrassed when someone else may hear it too).
With food involved or not, your digestive system has a two-hour cycle to ensure the intestines clean out. This involves a sweep of stomach acid through the system to get the job done. The noise of the liquid moving through is more pronounced when there is no food, but it can still happen right after a meal.
The express of gas from your mouth, better known as a burp, is not a stomach noise per se. As food or liquid is swallowed, it takes up space in your stomach. Sometimes this happens faster than the body can move the gas displaced by solids. Your stomach may get extended until the gas is expelled back up though your throat. The result is a burp, which can sometimes be rather pronounced.
Confusion with Other Issues
Significant intestinal noise accompanied with cramping and burping is a sign of your system building up painful gas as it is preparing to expel a bacteria or bad food. The later results could very well be vomiting or diarrhoea and more cramping. This type of body noise with related symptoms should not be ignored, and if there is excessive vomiting or bowel movement of liquid, rehydration with water and electrolytes is critical. Sport drinks can be very helpful.
If you have significant stomach noise with bleeding, violent nausea and/or vomiting, diarrhoea or constipation for more than three days, it's highly advised to see a doctor right away.