(TNS) — Holiday parties have a distinctive sound.

Glasses clinking. The jingle of seasonal music. Swells of laughter and periodic roars in conversation.

And occasionally, there are clusters of emphatic coughs from partygoers who talked or laughed a little too much while nibbling appetizers or sipping spritzers.

“It went down the wrong pipe,” they’ll announce as they recover, with a few slaps of their chest and a half-hearted laugh. But knowing what that common phrase actually means, which “pipe” it refers to and when the issue requires medical intervention, is almost as elusive as the Man in Red himself.

And knowing the difference could save a life.

“Normally, swallowing is an automatic process, a bunch of well-coordinated muscle interactions,” said Beckie Lemley, an Allegheny Health Network speech pathologist. She’s referring to a set of muscles that begin in the mouth — and include the tongue — which work to mash food, turning it into a “bolus,” or wad, that can be easily swallowed.

But right after swallowing, near the anatomic base of the tongue, is a Y in the road, where some of humans’ most primitive reflexes direct traffic between two “pipes”: the esophagus (or the “right” pipe), for food and liquids, and the trachea (or the “wrong” pipe), for air entering or leaving the lungs.

Ideally, the vocal cords and a flap of skin, called the epiglottis, protect the trachea while eating, allowing the esophagus to propel that bolus toward the stomach by sequentially contracting and relaxing.

“But anything that disrupts that normal, coordinated effort,” Lemley continued, “could cause something to sneak down the wrong pipe, as people say.”

A wide range of neurological conditions can interrupt those coordinated movements — such as history of stroke, multiple sclerosis, head trauma or Parkinson’s disease — as can eating or drinking too quickly or while talking.

“The good news is the reflexes we have are really good at protecting the airway from anything that irritates it,” said Andrew Perez, pulmonologist and chief of critical care at St. Clair Health. “Your symptoms can range anywhere from a tickle in the throat or cough to full-blown, ‘I can’t breathe,’ and someone needs to dislodge the food that’s blocking the airway.”

According to Perez, the misplaced food or liquid can simply sit on the vocal cords or epiglottis to cause this reaction but, in more severe cases, they can get sucked into the trachea and even into the lungs.

After a wayward swallow, the most dangerous sound to hear is silence, which can indicate a fully obstructed airway: no air moving in or out.

Other signs of true choking include one or both hands clutched around the throat, a look of panic, an inability to talk, strained or noisy breathing, squeaky breathing sounds, weak cough, or bluing of the lips, skin or nails.

In those cases — for anyone older than age 1 — the American Red Cross recommends first giving five back blows, which are more than haphazard whacks on the back.

While also preparing to call 911, support the person’s upper body as they bend at the waist, which exploits gravity to assist the expulsion of whatever is lodged in their airway. With the heel of your hand, give five back blows between their shoulder blades, then switch to five abdominal thrusts, otherwise known as the Heimlich maneuver. (Alternatively, only perform the Heimlich maneuver. No back blows required.)

If a person becomes unconscious, CPR should be the response, along with a 911 call.

But those are extremes.

More often, non-life-threatening lodged food (not cleared by a coughing fit) becomes the cause of a persistent hacking and an emergency room visit.

“Sometimes people will come in and say, ‘I feel like there’s something stuck in my throat, and it feels like it’s right here,’ and they’ll point to their chest,” Perez said.

What comes next depends on what went down the wrong pipe. Some medications or starchy foods will likely dissolve on their own in the warm, moist environment of the airway.

An X-ray is used to locate food or objects that show up well using that diagnostic, and can also spot collapsed areas of the lungs when a lodged object blocks the flow of air. A CT (computerized tomography) scan may be used instead. And a minor surgical procedure, known as bronchoscopy, could be used to retrieve an object, if necessary.

In any of those cases, infection of the lungs — pneumonia — is a possible outcome.

“The longer something is in there, you start to think about contamination with bacteria, and that will lead to a respiratory ailment,” Perez said. “You start looking for symptoms like coughing up yellow or green mucus and fever.”

And sometimes foreign bodies in the airway, also known as aspiration, can be more subtle.

“There are people where every time you watch them eat or drink, they’re coughing. They’re continually clearing their throats,” Lemley said. “Sometimes that means that food or liquid is sitting right on top of their vocal chords. They can sense it there, so they keep trying to clear it.

“If you’re sitting with your grandparent, and every time they take a spoonful of soup they’re coughing or clearing their throats, you might want to have them reach out to their physician.”

The next step would likely be a modified barium swallow study, she said, which makes a person’s upper digestive tract visible via continuous X-ray, called fluoroscopy, while their swallowing habits are observed.

Medical professionals can then see in real time whether swallowed materials get stuck, if each bolus requires multiple swallows to move toward the esophagus (when it should only require one), etc.

Much like instances of choking, however, the most dangerous type of aspiration is silent.

“These are the folks who don’t cough when something goes down the wrong pipe because they can’t sense it,” Lemley said. “That’s more problematic. These are the people who show up at the hospital with pneumonia for, seemingly, no reason.”

In many cases, the discovery of these swallowing differences leads to manageable changes to their eating habits, modifications like avoiding certain textures, turning their heads while eating or following up each bite with a sip of water.

And to some extent, otherwise healthy individuals could use some coaching, too, since many trips down the wrong pipe are avoidable.

“That’s a big take-home part of this. Eating is a very social thing, but it’s also something you want to be safe,” Lemley said. “As much as we eat and it’s a social activity, it’s important to stay focused while you’re eating. Don’t be talking while you’re eating. Chew your food, swallow, and then contribute to the conversation.

“Swallowing is a pretty automatic response, but there’s a lot that can go wrong with coordination when distracted.”