Why are some farts silent and others squeaky?

That's a lot of air. But each fart you release isn’t exactly the same. In fact, some sneak under the radar pretty subtly, while others, well, you can hear those go off from the next room.

So why do your farts sound different? And is there anything you can do to make a loud fart turn into a silent fart?

First of all, farts depend on a lot of variables, including what you eat, drink, and the movements of your bodies when gas escapes. Here’s what’s going on.

"As food is digested, gasses including carbon dioxide, methane and hydrogen build up within the intestines and seek their way out,” says Dr. Rice.

The intestines contract and move their contents including gas via peristalsis—or the contractions that move waste through your digestive tract—towards your anus. Small gas bubbles come together into larger gas bubbles en route to it exits, and when your body lets out those gases, that’s your fart.

Your fart sounds depend on the vibrations produced as the gas exits your anal canal, says Dr. Rice. Despite popular belief, your fart noises have nothing to do with the flapping of your butt cheeks.

"The sounds of farts are very much shaped by their expulsion velocity as well as the shape and size of the anal sphincter opening at the moment of passing," says Dr. Rice.

He compares it to a musical instrument: the smaller the size of the exit point, the higher the pitch—and perhaps more squeaky it will be. And the larger the opening at the moment, the lower the sound.

“There are likely many factors that determine the size of the anus in general at that moment of a fart, including general resting tone of the anus and other behavioral factors,” says Dr. Rice. “You can manipulate the sound of farts by relaxing and tightening the external anal sphincter and diaphragm to change pitch, volume and duration of sounds.”

That anal sphincter tightening similar what you’d do if you were trying to hold in poop, and since the opening would be tighter, that could lead to a squeakier, shorter fart.

And the expulsion velocity—or how fast the air is exiting your body—plays a role, too. If the air is coming out faster, your fart would be more likely to sound louder.

Plus, if swallowed air is triggering your fart—as is the case in the majority of farts—they tend to be louder (but less smelly), says Dr. Rice. If your fart is primarily driven from digestion and bacterial fermentation, it will tend to be smaller in volume and sound, but stinkier.

In most cases, whether your fart is loud, soft, squeaky, or sonorous, it’s really nothing to worry about. But there are some times when your farts may signal a medical issue.

"Consider seeking medical advice from your doctor if farts are associated symptoms of fecal incontinence, frequent involuntary passage of gas, persistent abdominal discomfort, abdominal distention or passage of blood," says Dr. Rice.

Your doctor may inquire about your diet, bowel movement pattern, family history, or other medical conditions and examine you to determine if you might have a medical condition that requires further evaluation or treatment for issues like irritable bowel syndrome (IBS), ulcerative colitis, colon cancer, or other gastrointestinal conditions