Why do burps make noise?

You can even form words or – for the truly talented – songs with burping.
You can even form words or – for the truly talented – songs with burping.

Parent24 is republishing Curious Kids, a series for children, with permission under a Creative Commons license.

Why does burping make noise? – Henry E., age 8, Somerville, Massachusetts

Burping is a normal part of everyday life.

Burps happen when air from your stomach travels back up your food tube – called an esophagus – to your mouth. Air gets into your stomach during activities like eating or drinking. If you drink things that contain lots of gas – like the carbon dioxide in bubbly sodas, for example – you’ll probably burp more than usual since the gas you swallowed has to come back out somehow.

Burping is important. If you don’t let the air in your stomach up and out, it heads down deeper into your digestive system. It can cause a lot of bloating and discomfort in your intestines.

That explains why people burp. But why does a burp make noise?

As the burp travels up the esophagus, it hits up against a closed, valve-like structure called a sphincter. Trapped behind that sphincter muscle, the gas builds up a lot of pressure.

Why do burps make noise?

A burp is gas that’s risen up to your mouth from your stomach via your esophagus. The sphincter at the top of your esophagus is like a gate that either keeps that gas in or lets it free.

Also see: What is the smallest animal ever?

It’s really hard to hold back a burp. When it finally forces its way through, the high-pressure air makes the structures in the upper esophagus and back of the throat vibrate – and that’s what causes the sound.

If you forcibly push the burp through, it increases the pressure in your esophagus, causing more intense vibrations and making the burp louder – more like a “BUURRRPP” or a “BRAAAPPP!” These are the belches that usually make your parents cringe and your friends give you high-fives.

If you gently open up your sphincter, it lowers the pressure in your esophagus and allows for less intense vibrations. These burps are more likely to be on the daintier side – more like a quieter “erp” – so probably your best bet for weddings or funerals.

The sound of the burp can take on even cooler and weirder tones depending on how you move your mouth and tongue around. This is how you can even form words or – for the truly talented – songs with burping.

So what happens if you have other gasses in the digestive system that are too far down to come up as a burp? That gas can become a fart. When you fart, gas leaves your body through another closed, valve-like structure – a different sphincter. This one happens to be called the anus.

As the gas builds up in pressure, often with a little help from your butt muscles, it causes that sphincter to finally open up. And the anus structures vibrate just like the structures in your throat during a burp. And there’s your fart.

So the next time someone says you’re burping too loudly, just reassure them that it was a perfectly normal mouth fart. That will probably go over well. You can always point out that at least it wasn’t a fart from the other end.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to curiouskidsus@theconversation.com.

Please tell us your name, age and the city where you live. We won’t be able to answer every question, but we will do our best.The Conversation

George Saffouri, Assistant Clinical Professor of Health Sciences, Gastroenterology & Hepatology, University of California, Riverside

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Chat back:

Share your story with us, and we could publish your mail. Anonymous contributions are welcome.

Sign up for Parent24's newsletters.

Read more:

We live in a world where facts and fiction get blurred
In times of uncertainty you need journalism you can trust. For 14 free days, you can have access to a world of in-depth analyses, investigative journalism, top opinions and a range of features. Journalism strengthens democracy. Invest in the future today. Thereafter you will be billed R75 per month. You can cancel anytime and if you cancel within 14 days you won't be billed. 
Subscribe to News24
Voting Booth
A Section 89 panel headed by former chief justice Sandile Ngcobo found President Cyril Ramaphosa has an impeachable case to answer on the Phala Phala scandal.
Please select an option Oops! Something went wrong, please try again later.
Ramaphosa should do the honourable thing and immediately resign.
24% - 1230 votes
Ramaphosa should follow due process and submit himself to an impeachment hearing.
30% - 1534 votes
Ramaphosa should fight the findings in court and keep his job at all costs
47% - 2409 votes
Rand - Dollar
Rand - Pound
Rand - Euro
Rand - Aus dollar
Rand - Yen
Brent Crude
Top 40
All Share
Resource 10
Industrial 25
Financial 15
All JSE data delayed by at least 15 minutes Iress logo
Editorial feedback and complaints

Contact the public editor with feedback for our journalists, complaints, queries or suggestions about articles on News24.