Asked by Peter Bettings
The origin of stomach rumblings comes from muscle contractions and ﬂuctuation. As food enters the gastrointestinal tract its walls squeeze the contents through the system at regular intervals to clear any potential buildup of food, gases and liquids. This ﬂuctuation is known as the basic electrical rhythm (BER). The speed and force of the muscle ﬂuctuations increases both in the presence of foodstuffs and also without them. In this latter case, the nerve receptors initiate a reﬂex generation of electrical activity, causing the muscles to contract and vibrate (ie rumble).