After taking meals most of us tend to belch. Some people even belch whenever they want to. Do you know why do we belch?
Every time we swallow food, a little air goes down with it. A muscular valve at the top of our stomach opens to let in whatever we have consumed and then closes quickly. This keeps strong stomach juices from sloshing out.
Usually, some air is always present in our stomach. A little gas is produced during the digestion of food. Sometimes carbohydrate bubbles in soda water enter the stomach when we drink soda water. It helps to release pressure of gas generated in stomach due to indigestion. When too much of air and gas collects, our brain gets a signal that something should be done. As a result muscles of our stomach tighten up and the valve opens. Thus we get a burp. The noise is produced by the air and the gas vibrating in the pipes that go out of our stomach. Thus we see that belching is a mechanism and a kind of reflex action by which the extra gases collected in the stomach are released.