THE MAN WHO GAVE THESE TWO THEIR BEEPS

IT’S A RISKY MOVE by anyone’s standards. Pixar’s delightfully adventurous robot-in-love story “Wall-E” boldly unspools without any human dialogue for the first hour or so. This trick seems akin to having R2-D2 carry half of a “Star Wars” film, speaking only in his emotive whistles, beeps and boops. In fact, Wall-E’s “voice” comes from the same source as R2’s idiosyncratic technobabble: Oscar-winning sound designer Ben Burtt.

In a renowned three-decade career with Lucasfilm, Burtt, 59, created everything from Darth Vader’s heavy breathing and Chewbacca’s yowl to the hum of lightsabers (the latter famously conjured from the sounds made by an idling movie projector and some chance microphone feedback). The native of Syracuse, N.Y., also came up with the signature crack of Indiana Jones’ whip in “Raiders of the Lost Ark.”

Soft-spoken and unassuming, Burtt is nevertheless sufficiently sound-fixated that he dots a phone interview with a few illustrative beeps and boops. Laughing, he remembers how “Wall-E,” which topped the box office this weekend, earning an impressive $62.5 million, came his way: “I had just finished my 29-year, 10-month tour of duty with ‘Star Wars,’ and I thought, ‘Well, at least I don’t have to do any more robots.’ But when Pixar called, I could see this was something more like a Frank Capra romance with Buster Keaton thrown in. And you had the challenge of not only creating the sound for this fantasy world, but the even bigger task of creating principal characters built out of sound.”

Opening on a toxic, abandoned future Earth, the movie introduces Wall-E (Waste Allocation Load Lifter Earth-Class) as a rolling trash compactor who’s developed a sweet-natured personality in his centuries of lonely service processing mountains of garbage. When a sleek robot called Eve lands for an environmental evaluation mission, Wall-E is smitten, determined to follow her to the ends of the earth and far, far beyond.

Director and co-writer Andrew Stanton (“Finding Nemo”) admits that at the outset, he didn’t know how he wanted his characters to sound -- hence his recruiting call to Burtt three years ago. The story brings to mind George Lucas’ “Star Wars” dilemma in the mid-’70s, when he needed someone to confect a whole galaxy of unusual ear candy, and found his and Francis Ford Coppola’s preferred sound man, Walter Murch, already booked. Lucas asked contacts at USC’s film school to recommend the next Murch, and was pointed to Burtt, then a standout student who held a bachelor’s in physics from Allegheny College in Meadville, Pa. Burtt would go on receive special achievement awards from the Academy of Motion Picture Arts and Sciences for his work on “Star Wars” and “Raiders” plus Oscars for “E.T.” and “Indiana Jones and the Last Crusade.” (Naturally, he also took part in the new “Indy,” supplying the otherworldly pulsation for the crystal skull of the title.)

Although layering in sound effects is a late-game process on many films, Stanton consulted with Burtt from the project’s earliest stages, much as Lucas did on “Star Wars.” Before there were even concrete visuals for Wall-E and friends, Burtt spent a year recording motors, fiddling with vocal manipulations on his computer and “auditioning” hundreds of audio clips for Stanton as they tried to find the characters’ voices, literally. Burtt estimates that he created as many as 2,600 sound files for “Wall-E,” as opposed to his usual 700 to 1,000 for a “Star Wars” installment or other special-effects films.

“We wanted to have this illusion that the voices for Wall-E and Eve and the other characters are part of their function,” Burtt says. “The idea is that there are little voice chips inside them creating their ‘dialogue.’ It’s audio puppeteering. Wall-E will look at something and there’ll be a little click of his hands or squeak of his head, and that’s all you need to give a sense of him.”

Among the more inspired sound sources for Wall-E’s movements: an old hand-operated generator that Burtt snagged online after remembering the device from a John Wayne film.

In the end, Burtt used his own heavily tweaked voice for Wall-E’s rudimentary speech. “I was experimenting with processing human voice input,” he says, “and it was like Dr. Jekyll in his lab: ‘Well, there’s nobody else around -- I guess I’ll drink the potion.’ ” Audiences have an infinitely easier time recognizing Sigourney Weaver as the computer voice of the Axiom, the space-faring cruise ship that 28th century mankind calls home. “I thought it would be so funny if Ripley was now Mother from ‘Alien,’ ” Stanton says. “She’s sci-fi royalty.”

One imagines there must have been development meetings in which Pixar had its Disney partners fidgeting over it taking so long for the familiar voices of Weaver and others to turn up. After all, might not an average 6-year-old fidget too? “It was just luck, but the movie’s formative years came during Disney and Pixar’s [threatened 2005] divorce, so there was a distraction,” Stanton says. “By the time people started paying attention, it was obvious it was working.”

While Pixar’s gambit with dialogue can be seen as ambitious (or even risky), there are creative precedents for what they have done. “There have always been mute characters,” notes Jerry Beck, an animation historian and co-writer of the blog Cartoon Brew. “Road Runner, Tom and Jerry, the Pink Panther. But that’s what Pixar does -- they take classic animation elements and create something new. And don’t forget, their logo is that Luxo lamp -- an inanimate object communicating through movement and sound effects, but no dialogue.”

In the end, Stanton had his own issues with speechlessness when making the movie. “It took me probably the entire first year to get over the fact that I was working with Ben Burtt, one of my heroes,” he says. Laughing, he adds, “I tried not to reference ‘Star Wars’ when we were working. But I did have one moment where I needed a sound, and finally, I said, ‘All right, Ben, you know in ‘Episode IV,’ when they’re in the sand crawler?’ ‘Oh yeah, the gonk-gonk robot.’ ‘Yeah, I’m looking for that.’ ”