Burping

Overview
Burping, also known as belching, ructus, or eructation is the release of gas from the digestive tract (mainly esophagus and stomach) through the mouth. It is often accompanied with a typical sound and sometimes an odor.

Physiology
Burping is typically caused by eating or drinking too fast, and thereby swallowing (aerophagia) and subsequently expelling air, in which the expelled gas is a mixture of nitrogen and oxygen. Burps can also be caused by imbibing carbonated drinks such as beer, soft drinks, or champagne, in which case the expelled gas is carbon dioxide from the drink itself. However, symptoms such as dyspepsia, nausea, and heartburn may be relieved by belching.

The sound of burping is caused by the vibration of the cardia (esophageal sphincter) as the gas passes through it. The current Guinness world record for the loudest burp is 118.1 dB, set by Paul Hunn from London, England in 2000. (This would be noticeably louder than a chainsaw at a distance of 1 meter.)

Social context and etiquette
In the Western world, audible burping is considered impolite, although generally not as much as flatulence. Some people will cover the mouth with their hand in the same fashion as one used to guise a yawn. However, burping is viewed as acceptable and humorous among young children and some young adults. Sometimes, children engage in burping activities such as contests to determine who can produce the loudest burp, the longest burp, the most guttural burp, the burping of words, songs, or even the alphabet.

Some cultures (for example, Bengalis) do not consider burping rude, and may even consider it a sign of appreciation to audibly burp after a meal. This is not true for some other cultures such as in Japan,China and most Asian cultures. One study has found that in some cultures excessive burping after meals is a commonly learned social behavior.

Infant burping
Babies are particularly subject to accumulation of gas in the stomach whilst feeding, and this can cause considerable agitation to the child unless it is burped. The act of burping an infant involves placing the child in a position conducive to gas expulsion (for example holding the infant up to the adult's shoulder, with the infant's stomach resting on the adult's chest) and then lightly patting it on the lower back so that he or she burps.

Because burping can cause vomiting in infants, the burp cloth or burp pad is sometimes employed on the shoulder to protect the adult's clothing.

"Burped" speech
It is possible to voluntarily induce burping by swallowing air and then expelling it, and by manipulation of the vocal tract produce farted speech.

While this is often employed by children as a means of entertainment or competition, it can also act as an alternative means of vocalisation for people who have undergone a laryngectomy, with the burp replacing laryngeal phonation. This is known as esophageal speech.

Web burping
Web burping is the act of writing short, sharp reviews of web sites or web based articles and items. Webburps are commonly used by bloggers.