In 2005, Barry Marshall, an Australian gastroenterologist and researcher, shared the Nobel Prize in Medicine for the discovery that peptic ulcers are caused not by stress, as was commonly thought, but by a bacterium called Helicobacter pylori. (Marshall, the director of the Marshall Centre for Infectious Diseases Research and Training, at the University of Western Australia, proved this in part by ingesting H. pylori himself and becoming ill.) The finding meant that ulcers could be treated with antibiotics, and it has made stomach cancer, often associated with ulcers, a rarity in developed countries.

Marshall has also spent considerable time confronting another common gut ailment, irritable-bowel syndrome, or I.B.S. “It occupies about thirty per cent of my practice,” he told me recently. I.B.S. is a complex of conditions that is defined mainly by its broad array of symptoms, which can include stomach pain, bloating, cramps, diarrhea, constipation, or any combination thereof; eleven per cent of Americans suffer from it. “It’s a diagnosis of exclusion,” Marshall said, meaning that it’s the vague category of what’s left over when more serious possibilities are ruled out. As a result, patients often must endure a steeplechase of uncomfortable tests—colonoscopies, biopsies, stool samples—only to learn, months later, that they have I.B.S., which can be treated with medicine, changes in diet, or both.

Marshall now thinks he’s found a way to diagnose I.B.S. quickly and directly: by listening to it. Earlier this week, at the annual Digestive Disease Week conference, in Washington, D.C., Marshall described a device that he and colleagues are developing: a wide belt, to be worn by the patient, that records the creaks and undulations of the gut, analyzes them with software, and recognizes the distinct sonic signature of I.B.S.

For centuries, physicians have used their ears to pick up hints of trouble in the heart and lungs. In theory, I.B.S. should succumb to a similar approach. Marshall described the ailment as “a motility problem”—an abnormal movement of matter and gases through the intestines, producing a wild range of sounds as the bowel squeezes harder or softly at different times in different places. But the gut, unlike the heart or lungs, is more than twenty feet long, and, although physicians can listen to it, “they don’t listen long enough, and it’s hard to know what to listen for,” Marshall said. He began to imagine a high-tech gadget that could listen for a couple of hours, parse the many frequency patterns, and analyze the results. “That was just a concept,” Marshall said. “When we started, it wasn’t obvious that this would work.”

Marshall drew his inspiration, in part, from his son, who helps analyze seismic data from the seabed for hints of undiscovered reserves of petroleum. Marshall also knew about gunshot-detector systems, arrays of acoustic and optical sensors—deployed in war zones and in some cities—that can pick out the sound of a gunshot from background street noise and locate precisely where it occurred. Then a colleague showed Marshall a store-bought acoustic device, about the size of a quarter, used for detecting termites.

“You pin it under your house and it picks up any scratchy little noises in there,” Marshall said. “You could almost swallow it—or stick it on different parts of your abdomen.” The medical device that Marshall envisaged would be “almost like putting a G.P.S. locator on the gut,” he said. “You could figure out approximately where the problem is if you listened for long enough and processed the data in just the right way.”

The physical device is straightforward—it consists of a Velcro waistband, “like what the workers at the airport wear to support their backs,” Marshall said, that contains a series of pea-size microphones. (“We were looking for something you could put directly on skin without it being too prickly,” he said.) Next, they brought in about seventy volunteers, half with I.B.S. and half without, and recorded the sounds of their innards, for two hours, after fasting, and again, for forty minutes, after a meal. The team’s mathematical engineers then reduced the noise into two dozen or so distinct frequencies, while the software juggled another thirty-odd parameters, including the duration and scale of the sound, where in the gut it occurred, and what sounds occurred just before and after.

Gradually, they trained the software to recognize a sonic signature for I.B.S. and to distinguish patients who had the ailment from those who didn’t. When they tested the device on thirty more volunteers, fifteen of whom had I.B.S., it correctly identified thirteen of them—an eighty-seven-per-cent success rate. It’s a very small trial, Marshall noted, but, as the software listens to more intestines, it will become even better at discerning healthy from unhealthy.

Listening to a recording of the intestines is like hearing the soundtrack of a Jacques Cousteau film: there are clicks, burbles, and groans, sometimes coming rapidly, sometimes interspersed with periods of silence. Marshall conceded that the work of the diagnosis is a bit of a black box; he couldn’t pick out the sounds of I.B.S. by ear any more than his son could discover an oil deposit just by listening to the audio of seismic waves. “At the moment, it’s all happening inside the machine,” he said. “It’s all about the algorithm that comes out of it. It’s like the secret recipe for Coca-Cola.”

Nonetheless, Marshall said, an accurate device could serve as a quick, noninvasive screening tool that could spare patients unnecessary testing and discomfort. “It could be a pretty normal part of workup before moving on to bioscopies and colonoscopies,” he said. And physicians would have any easy, quantitative way to determine whether and how well any prescribed treatments were working. Conceivably, the device could be rented from a pharmacy or a health clinic and the results uploaded for analysis by a doctor.

Marshall mentioned that his son’s work entails turning seismic data into three-dimensional visualizations of the seabed that can be manipulated on a V.R. headset. “You can move it apart, like Superman going through the Earth,” he said. He didn’t sound terribly interested in touring the human gut in a similar manner. Besides, he said, “it’s not as simple as you might think”; the gut is a living thing, and stuff is always moving through it. Meanwhile, Marshall’s daughter had invited him to a different sonic scene, also mushy underfoot: the Bonnaroo Festival, in Tennessee, this weekend. “I’ll probably be wading around in the mud with a bunch of hippies,” he said. “It should be interesting.”