Thanks to Auto-Tune, T-Pain’s vocal hooks can sound delirious. Illustration by Puny

Tourists black out reflective retinas in snapshots before printing them, and millions of people refer to strangers they’ve never spoken to as friends, because they’ve connected through a social-networking platform. The transition from living in the stubborn physical world to managing a life that is split between platforms, where the ability to change aspects of your identity (at least digitally) is always an option, is becoming more common. It should come as no surprise, then, that singers sometimes choose to correct recorded flaws in pitch with modern software, like Antares’s Auto-Tune.

Andy Hildebrand, Auto-Tune’s inventor, spent eighteen years in a field called seismic data exploration, a branch of the oil industry. He worked in signal processing, using audio to map the earth’s subsurface. His technique involved a mathematical model called autocorrelation. The layers below the earth’s surface could be mapped by sending sound waves—dynamite charges work nicely in unpopulated areas—into the earth and then recording their reflections with a geophone. As it happened, autocorrelation could detect pitch as well as oil, and Hildebrand, who had taken some music courses, turned his engineering skills toward pop.

Most of the time, Auto-Tune is used imperceptibly, to correct flat or sharp notes. The New York producer Tom Beaujour, who records rock bands that sound nothing like contemporary R. & B. or pop, says that it gets used, in one way or another, in almost every session that he works on. Often, it solves logistical problems: an artist has left the studio and has no opportunity to return just to re-sing one or two off notes.

But pitch correction has also taken on a second life, as an effect. You’ve probably heard it, most recently on the No. 1 song in the country, Lil Wayne’s lazy, mildly naughty rap “Lollipop.” Auto-Tune, properly torqued up, is the rare edit that calls attention to itself. Auto-Tune software detects pitch, and when a vocal is routed through Auto-Tune, and a setting called “retune speed” is set to zero, warbling begins. This, roughly, is what happens: Auto-Tune locates the pitch of a recorded vocal, and moves that recorded information to the nearest “correct” note in a scale, which is selected by the user. With the speed set to zero, unnaturally rapid corrections eliminate portamento, the musical term for the slide between two pitches. Portamento is a natural aspect of speaking and singing, central to making people sound like people. A nonmusical example of portamento would be “up-speak,” a verbal tic common in some people under thirty. (Can you imagine the end of every sentence rising in pitch? Like a question?) Processed at zero speed, Auto-Tune turns the lolling curves of the human voice into a zigzag of right-angled steps. These steps may represent “perfect” pitches, but when sung pitches alternate too quickly the result sounds unnatural, a fluttering that is described by some engineers as “the gerbil” and by others as “robotic.”

The first popular example of Auto-Tune’s distorting effect was Cher’s 1998 hit “Believe,” produced by Mark Taylor and Brian Rawling. During the first verse, Auto-Tune makes the phrase “I can’t break through” wobble so much that it’s hard to discern. More successful is the gentler variation in the following line, “so sad that you’re leaving,” which highlights the software’s strength. Auto-Tune can produce a controlled version of losing control, hinting at various histrionic stations of the human voice—crying, sighing, laughing—without troubling the singer. It is notable that “Believe” ’s big chorus—“Do you believe in life after love?”—is delivered (mostly) in a full, human-sounding voice, with no robotic modifications. You can only feel so bad for a robot.

Before “Believe,” Auto-Tune was a closely held producers’ secret. (“They didn’t want to be known to manipulate the pitch of sound,” Hildebrand says.) After “Believe,” radical pitch alteration showed up repeatedly—in, among other places, a chunk of Madonna’s “Music” album, from 2000, Jamaican dancehall singles, and pop hits like JoJo’s “Too Little Too Late,” which uses a human-to-robot ratio very similar to that of “Believe.” In the manual accompanying Auto-Tune’s fifth-release version, the zero speed setting is described as “the Cher Effect.”

No one has used Auto-Tune’s zero speed setting more consistently and successfully than the R. & B. singer T-Pain. Born Faheem Najm, in Tallahassee, he has become such a common guest on pop records that in a single week last year he was featured on four singles in the top ten of the Billboard Hot 100 chart, including the No. 1 song, Chris Brown’s “Kiss Kiss.” In the same way that the dry, flat drum sounds in Fleetwood Mac’s “Rumours” will forever say “mid-seventies,” T-Pain and Auto-Tune will forever remind people of the late aughts.

T-Pain, who is currently working on his third album, “Thr33 Ringz,” spoke to me on the phone from his studio in Miami. He first heard the Auto-Tune effect on a song by Jennifer Lopez—he doesn’t remember which one—and borrowed it for a mixtape appearance in 2003. He says it’s no trade secret that he uses Auto-Tune with the retune speed set to zero, and likes to recall a time he spent selling fish out of a truck with his father in Tallahassee: “My dad said, ‘They can know what you’re using, but they’ll never know how to use it. They can see that we’re using salt and pepper.’ ”

The Auto-Tuned T-Pain is rarely a mopey presence. In his hands, the program becomes pop music’s rose-colored glasses, or a balloon’s worth of helium inhaled. His vocals hang, flickering, and suggest not a technological intervention but a chemical one. His vocal hooks sound delirious, not desperate.

Someone once asked Hildebrand if Auto-Tune was evil. He responded, “Well, my wife wears makeup. Is that evil?” Evil may be overstating the case, but makeup is an apt analogy: there is nothing natural about recorded music. Whether the engineer merely tweaks a few bum notes or makes a singer tootle like Robby the Robot, recorded music is still a composite of sounds that may or may not have happened in real time. An effect is always achieved, and not necessarily the one intended. Aren’t some of the most entertaining and fruitful sounds in pop—distortion, whammy bars, scratching—the result of glorious abuse of the tools? At this late date, it’s hard to see how the invisible use of tools could imply an inauthentic product, as if a layer of manipulation were standing between the audience and an unsullied object. In reality, the unsullied object is the Sasquatch of music. Even a purely live recording is a distortion and paraphrasing of an acoustic event.

Sir George Martin, via e-mail, wrote to me about his work with John Lennon, one of the most famously processed voices in pop history. “It’s true that John was never satisfied with the sound of his voice,” Martin explained. “He failed to realize that what he heard came through the bones of his body and was not his true sound. He was always looking for perfection, and in his imagination his voice was always superior to the sound of anything on tape.” To paraphrase, what we hear on Beatles records is Lennon’s imagination. T-Pain’s deployment of Auto-Tune is a similar assertion of self, no different in kind from the older, more traditional tricks of tape-splicing, double-tracking the voice, and adding a little reverb.

When I asked T-Pain if he could ever forgo Auto-Tune, he said, “I got a song on my album about my kids. I ain’t use it on that one.” ♦