Distension can follow food or air swallowing. Sudden changes in temperature, excess alcohol or tobacco can also lead to hiccups, as can psychological causes such as excitement or stress.
Chronic burping is caused by constant, unconscious air swallowing, often from anxiety (hyperventilating increases the amount of air we swallow, thereby increasing gas).
With your mouth closed, inhale slowly through your nose (expanding your abdomen--not your chest), then slowly exhale through your mouth (this helps to prevent air swallowing and hyperventilation and seeks to stimulate the vagus nerve to pass gastric contents "downstream").
Putting the Brakes on Air Swallowing. Although belching is almost always harmless, it provides no lasting relief and is a social no-no in polite company, at least in the U.S.