Curious Kids is an educational series. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au. You might also like the podcast Imagine This, a co-production between ABC KIDS Listen and The Conversation, based on Curious Kids.
Why are burps so loud? – Byron, age 6, Sydney.
That’s a great question, Byron. Some burps can be really loud, but they can be quiet, too. How loud a burp is depends on a few factors, like how much gas is in your stomach to burp up and the structure of the food pipe that the burp travels along before it leaves your mouth. Let’s look at burps in a bit more detail.
What is a burp, exactly?
The word “burp” describes the release of gas in your stomach or food pipe that occurs after you eat and drink. The scientific name for the food pipe (also called the gullet) is the esophagus. The esophagus, which is about the size of a ruler and connects your stomach to the back part of your throat, is a muscular tube.
What is the source of the burping noise?
You can see this tissue if you open your mouth wide and look in a mirror. The epiglottis is what you see. The epiglottis tilts back when you swallow to block the windpipe leading down to your lungs. This means that the opening of your food pipe has become clear. The epiglottis acts like a traffic control.
The epiglottis is the most important part of the esophagus. Shutterstock
When you burp, gas is trapped in the stomach and upper esophagus. Gas is usually under pressure when it is present in large quantities. As the gas is pushed up through the food pipe and over the top of the esophagus, the surface of your upper esophagus vibrates and rattles. This is similar to windows that rattle in a storm. Another factor is the long, round shape of the esophagus. This causes the sound to echo up the food pipe.
You can make your burp louder or quieter.
Take a cardboard tube out of a roll of lunch wrap or toilet paper. Put your lips on the end of the line and hum softly. The echo makes the noise louder than when you buzz without using the tube. Please do it again, but this time with a lot more power. The sound is now much more audible. The echo is more audible when you force more air through the tube. It is because of this that larger burps sound louder.
The size of your food pipe and the amount of gas in it will determine whether you burp louder or softer. When there is a strong wind blowing, windows will rattle more than when it’s calm.
You can burp loudly if you consume a large can of soda water. Take lots of gulps to swallow more air.
Babies have smaller stomachs and smaller food tubes, so their burps are quieter than those of children or adults.
Where does gas come from?
Gas can come from several different sources. You can get gas from the air you swallow while eating and drinking. When people drink through a straw or eat fast, they can consume more air. When you drink soft drinks, the “fizz” is carbon dioxide. Other gasses are also produced in your intestines during digestion.
