Rachel Kenny started listening to podcasts in 2015 — and quickly fell behind. "As I started subscribing to more and more podcasts, they started stacking up, and I couldn't keep up at normal speed," the 26-year-old data scientist in Indianapolis told BuzzFeed News. "I also had to listen to the backlist of all the podcasts when I subscribed to them." So Kenny began listening faster: first at 2x, then she worked her way up to 3x. She stopped only because "that's just as fast as the Downcast app allows." She estimates that she listens to five to seven hours of podcasts a day (which equals 15 to 21 hours at normal speed), "so maybe 20 to 40 episodes a day or 100 to 250 a week," she said. She tracks her listening habits on a spreadsheet. Kenny's listening habits may be extreme, but she's not alone. Meet the podfasters, a subset of podcast obsessives who listen to upward of 50 episodes a week, by, like Kenny, listening extremely fast. They're an exclusive group: According to Marco Arment, creator of the Overcast podcast app, only around 1% of Overcast listeners use speeds of 2x or higher. (An app called Rightspeed, which costs $2.99, allows you to listen at up to 10x.) Podcast consumers listen to an average of five podcasts per week, according to a recent study, which seems like a nice, manageable number: enough time to listen to a true crime podcast or two, a long comedy podcast, maybe a dash of politics. But for some people, that's just not enough: Over 20% of podcast consumers listen to more than six per week, and podfasters — well, they listen to a lot more.

Aj Mast for BuzzFeed News Rachel Kenny listening to a podcast in her car.

You could read these tendencies as a symptom of our sped-up culture, of a listening population too impatient or distracted to listen to anything for longer than, say, half an hour. But also, in the same way that peak TV and streaming has led to a culture of bingeing shows, we're now in peak podcast — there are a lot of good shows, and not enough time to listen to them. But in conversations with people who listen at speeds higher than 2x, it became clear that many podfasters are above all, completists. That is, they have an almost obsessive need to listen to every episode of a podcast that they decide to commit to. Take 34-year-old Jason Strickland, who works for a land surveyor in Winston-Salem, North Carolina. He listens to around eight hours of podcasts at work every day, and listened at normal speed until he came upon the Movies by Minutes series of podcasts, which analyzes iconic movies minute by minute. (In other words, every episode is devoted to one minute of a movie.) When he found it, the hosts had already completed the original Star Wars trilogy, which was 378 episodes, plus a few special episodes, so he started downloading 50 episodes at a time and listening at 2x speed. "It took about a month per movie to get caught up," he said, explaining that he would listen to whatever podcasts were on his current listening list in the morning, and then power through the Movies by Minutes episodes in the afternoons. "Once I was current, I would then go find another show to download and get caught up, repeating this for all the shows."

"I have often, when finding out about a new podcast with a large back catalog, made myself a 100-hour-plus playlist to catch up."

Sam Borley, a 28-year-old charity shop worker in Felixstowe, England, listens to his 56 weekly podcasts at different speeds, calibrating each one depending on the content and how fast or slow the hosts speak, though he said he listens to most at speeds between 2x and 3x. Like Kenny, when he finds a new podcast, he makes a point of listening to the entire back catalog. "I have often, when finding out about a new podcast with a large back catalog, made myself a 100-hour-plus playlist to catch up, and then set my favorites to automatically jump the queue and play next so I can catch up on some without falling behind on others," he said. "The Joe Rogan Experience, for example — it's up to nine hours a week of content, so it would be hard enough to keep up with that one alone if not listening at faster speed." Laura McCavera, a second-year medical student in Vegas, said she started out listening to her medical school lectures at faster speeds before using the practice with podcasts as well. When she starts a new podcast, she begins at normal speed "to get a sense of the cadence, and then I increase it as necessary," maxing out at 2.5x. She compared listening to a sped-up podcast to skimming a book, explaining that podcasts are easier than lectures to listen to casually, “so it's less stressful to try to make sure you get every word." Podcast producers and hosts were mixed on their feelings about podfasters. Georgia Hardstark, who cohosts the Apple Podcasts top 25 My Favorite Murder podcast with fellow comedian Karen Kilgariff (tagline: Stay sexy, don't get murdered), said it doesn't bother her: "Everyone's brain works at a different pace so it doesn't worry me. Plus each person listens to a podcast for a different reason, so if they're just looking for information and not humor, then they won't be missing anything." She added that she personally listens to some podcasts at a slower speed when she's trying to fall asleep. Gina Delvac, the producer of Call Your Girlfriend, in which long-distance best friends Ann Friedman and Aminatou Sow catch up weekly about women's issues, said she understood how someone would listen to CYG at a faster speed. "It's loose, it's conversational, it's meant to feel free-flowing. But for some programs I've worked on, or if you think about people who do really densely produced stuff, there's a whole experience that's built around that kind of audio experience." She added, "I don't have hate because I'm very intrigued by how people decide to consume what we make." Some podcast apps include a feature that automatically gets rid of pauses, which Delvac is more conflicted about. "There are kinds of intentional storytelling where you put a pause in there for a reason.” But Eric Eddings, host of The Nod, feels that sped-up listening is unequivocally bad. "I don't think it should ever happen," said Eddings, who used to host the now-ended podcast For Colored Nerds. "The shows I've worked on have all been really sound- and music-rich. And you're just fundamentally gonna miss that if you're listening at even 1.5." He recalled the first story he ever produced, about some men from his mother's hometown in Louisiana. "It was just stacked with things that would not work at 1.5 speed. You have all these elderly Southern men recounting their life, which is really serious and intense. On top of that, we had sound effects and scoring music coming in. We took a song from this meeting that happened in the '70s and slowed it down and built it into the episode. My soul dies when I think of somebody listening to that at 1.5 or 2."

AJ Mast for BuzzFeed News Rachel Kenny increasing the playback speed of a podcast.

In June, Apple announced that it would be opening up its analytics to allow podcast producers to be able to see just how many people were listening to their podcasts — including how many of them were skipping over the ads. Many podcast ads are direct response — that is, they give you a code to use for a discount on a product — so this has, until now, been the best way that advertisers could measure the effectiveness of their ads. But if people are listening to podcasts at very fast speeds, does that diminish their value to advertisers?

Lex Friedman, chief revenue officer for Midroll Media, a large podcast ad network and owner of the Earwolf network of podcasts, said no — and in fact, podfasters could potentially be more valuable to advertisers because they may be less likely to skip ads. Friedman himself listens to podcasts at 1.8x. "I think people like me are less likely to skip ads because they're wasting less time when they're listening," he said. He added that he's never heard an advertiser complain about podfasters. "I really do genuinely believe that if it's having any effect on ads, it's making them more likely to be heard. Now they'll pay attention to the ads. I don't think it harms the ads' efficacy." In fact, according to behavioral neuroscientist Stephen Porges, because recordings played at higher speeds are at a higher pitch, they are actually easier to hear. Low-frequency noises, like street noise, vacuum cleaners, or airplanes, get in the way of our understanding of people talking; by playing podcasts at a higher speed, the listener is creating a greater acoustic differentiation between the words and lower-frequency background noises. According to Porges, the muscles in the middle ear help to dampen low-frequency sound so we can hear speech more clearly — but if we don't exercise those muscles (by, say, not having much human interaction), then they don't work as well. Thus, listening to things at a higher frequency, and speed, could be helpful.

Megan Mack for BuzzFeed News Rabbi Mordechai Lightstone listening to a podcast on the walk home from work.