Television producer Lee Mendelson was already a few years into his collaboration with Peanuts creator Charles Schulz when he was faced with an unusual problem: How do you depict adults in an animated special for a comic strip that never features adults?

Mendelson, Schulz and animator Bill Melendez had been collaborating on Peanuts specials since the Emmy-winning A Charlie Brown Christmas, but the newest one, 1967’s You’re in Love, Charlie Brown featured a classroom scene and some interaction with a teacher, Miss Othmar.

Now 82 and living just outside San Francisco, Mendelson told Mashable, “We chose not to show the adult. So I asked our music director, Vince Guaraldi, ‘Would there be some instrument we could use as a sound to emulate what an adult might sound like to a kid?’”

Guaraldi, who first collaborated with Schulz and Mendelson on a 1963 documentary about the comic strip legend, didn’t hesitate. He brought in a trombone player.

While the name of the musician has long since been lost, Mendelson said, “He was the first one, he worked and that was it.”

They played the sound for Schulz who said, according to Mendelson, “That’s great.” Everyone, including the network and the sponsors, embraced it. Critics called it innovative. The team never got any audience feedback on the sound, though it was clear they accepted and, perhaps, even embraced it.

“It became our off-stage voice forever,” said Mendelson, who served as Executive Producer on the Peanuts specials.

The Wah Wah Machine Image: Peanuts, : Blue Sky Studios, 20th Century Fox Animation

Now it can be your voice, too. As part of the promotion leading up to the release of the first-ever CGI-animated Peanuts movie, Blue Sky Studios and the Peanuts organization are launching “The Wah Wah Machine.” It’s a web site where you can turn any word or phrase you type in into the Wah Wah “language.” Yes, you can share this stuff out starting on Monday.

The new movie will, naturally, feature that same adult “wah wah” sound. In fact, there was “never a moment’s conversation” about using real adult voices, said The Peanuts Movie director Steve Martino. Martino told Mashable that numerous people came up to him and offered to “make” the sound with their own voices. “Many didn’t know its done quite wonderfully by a trombone player,” he said.

Trombone Shorty uses a trombone to recreate the iconic wah wah sound for the upcoming Peanuts Movie. Image: Peanuts, : Blue Sky Studios, 20th Century Fox Animation

Eventually, he found trombonist Trombone Shorty (a.k.a. Troy Andrews) and set about recreating the “wah wah” sound people hear in their heads.

“Trombone Shorty came in with a little arsenal. I didn’t realize there were so many different kinds of plungers or mutes,” said Martino. “We tried many different styles and found one particular one that gave us just the right sound.”

That became the go-to mute for all the Peanuts’ treacher Miss Othmar’s “wah wahs.” Martino and Trombone Shorty then focused on using the trombone to vocalize actual lines they had written for the adults, but would only be heard as wah wahs.

The sounds in the “Wah Wah Machine” are also all from Trombone Shorty and his pitch-perfect mute.

Peanuts Director Steve Martino (left) feeds Trombone Shorty lines that he'll convert into wah wahs for the movie. Image: Peanuts, : Blue Sky Studios, 20th Century Fox Animation

It’s worth noting that the wah wah sound was not a part of the original Peanuts special, according to Mendelson, who is, naturally, a font of information about classic Peanuts animated specials, including the very first one.

It almost didn’t make it

From the start, the Charlie Brown Christmas special was, in a way, revolutionary. As Mendelson explained:

Nobody had ever used real kids before. Cartoons always used adults to play kids. Nobody ever mixed jazz, Beethoven and traditional Christmas music before. No one had every animated a scene from the bible before.

And thanks to Charles Schulz, it didn’t even have a laugh track. That was the only bit of disagreement between Mendelson and Schulz. “I said I think we should have a laugh track, since most cartoons did back then. And Mister Schulz said, ‘No laugh track,’ and that was then end of the only dispute we had.”

The 25-minute special (“It was planned down to the second, “said Mendelson) was unlike anything that had come before it and that was almost its doom.

Halfway through the production of A Charlie Brown Christmas a man came over from the ad agency to see how we were doing and of course by then all we had was black and white and no music and he thought it really looked really very bad. And he said if I go back to the agency and tell them what I am seeing and feeling, they may cancel the show. I said to him, ‘Please trust in Charles Schulz and his characters, which already imparts so much joy to so many people.’ And he smiled and said, ‘Okay, I’ll take a chance with you.’ And we kept producing.

By the time the show was finished, Melendez, Mendelson and Schulz knew they had something special, but no one was sure if audiences would like it. The sponsor, Coca-Cola was on-board, but equally skeptical about its success.

Mendelson explained that they screened it for a bunch of male Coca Cola ad execs who weren’t sure if it worked or not. But Mendelson had an idea.

“I asked them, ‘Would you please have all your wives and kids and girlfriends come in to watch it?’ They did that, and of course, everyone loved it and [Coca-Cola was] thrilled. That was one of my better moves,” said Mendelson.

Character art and many of the ideas in the Christmas special came directly from Schulz, but the team collaborated on some and others came directly from animator Melendez. He cooked up how the characters would dance and is responsible for Snoopy’s voice (which you will hear again it the new movie).

Mendelson lifted the idea of a sorry-looking Christmas tree from Hans Christian Anderson’s The Little Fir Tree. Schulz and Mendelson came up with the look of the iconic (and beloved) tree together.

The stories

The Christmas pageant story came directly from Schulz’s daily comic strips, as was 1966’s It’s the Great Pumpkin, Charlie Brown, (Mendelson’s other favorite). However, with more than 40 Peanuts specials, the team eventually started creating stories “out of whole cloth.” Of course, Mendelson told Mashable, the characters were always true to the comics. “If Linus was in Europe, he had his security blanket,” said Mendelson.

Today, Mendelson is all who remains of the original Peanuts special team. Melendez died in 2008, Guaraldi in 1976 and Charles Schulz in 2000. Mendelson has no involvement with the new film, which he has previewed, but he is looking forward to it. “The movie is terrific, it’s a seamless transition from our animation to the new animation and hopefully they will coexist for many decades.”

In the meantime, you can celebrate what Mendelson, Melendez, Guaraldi and Schulz created by getting your wah wahs on.