Take a spin around the radio dial.

The hip-hop station is keeping the neighbors awake with bass-thumping sounds of "Hoh! Abba Dah No"; the jazz station is featuring a mellow instrumental, "Prah Sesst Chi"; and the Top 40 crowd can't get enough of "Eeyooma Mana Muki Vop."

Such is the musical world of The Sims.

For years the virtual denizens of the Sims universe have been rocking out to tunes sung in a language only they can understand.

For the real-life humans behind the scenes, creating these audio concoctions takes as much work as recording a full-length CD. The Sims games have a tradition of marrying infectious melodies with nonsensical lyrics to create tunes that you want to hum, but can never quite sing along to.

Maxis audio director Robi Kauker is the man in charge of making sure that the rap, salsa, heavy metal, or pop songs sound like the real thing and feature top-quality production values. Each song has to be iconic to its musical style but, at the same time, variety is vital. Kauker knows diehard Sims fans spend virtual lifetimes playing, so the music can't be repetitive.

For the music in The Sims 2, composing and recording the musical tracks took about a year. Kauker said getting performers to abandon English and sing in Simlish, the made-up language of the Sims, was easy.

"You'd be surprised how much the singers like it," Kauker said.

Many artists, he notes, use their own form of Simlish when composing songs, and fill in real words later. It's not unlike the famous story of Paul McCartney, who reportedly used "scrambled eggs" as a placeholder when writing "Yesterday."

Rappers seem particularly adept at adapting to Simlish, and many have fun with it by adding secret messages, Kauker said. Laced among the gibberish, some singers will give a shout-out to their buddies by hiding friends' names in the lyrics. Kauker said the Maxis crew doesn't mind, as long as it's not obvious. That Easter egg tradition was started by Drew Carey, who appeared as a celebrity Sim in the House Party expansion and hid a friend's name in his Simlish dialogue.

In setting the tone for the Sims 2, Maxis enlisted Mark Mothersbaugh, a founding member of Devo. Mothersbaugh composed the theme and music for the create-a-Sim portion of the game.

But for the music within the game itself, Maxis looked to replicate the variety of musical styles available on the radio. The developers turned to several producers, including the Humble Brothers, a pair of music mixers and composers who live up to their name by fiercely guarding their anonymity. The Brothers have worked on other games, as well as projects in the mainstream music industry. Their first hit was a mix of Linkin Park's "1stp Klosr."

Recording one of the Simlish tracks costs as much as recording a regular song. The Brothers use a different lead vocalist on each track, and finding the right voice sometimes means auditioning three or four performers. Occasionally, an artist just can't wrap their mind around the Simlish concept and, after hours of trying, the producers have to start from scratch with someone new.

In some cases, after the artists get paid for the work, the Brothers find they've taken a loss on the project. But they don't mind because they feel they're creating art and they own the rights to all the music they create.

Some of the songs may get a second shot at the limelight, as the Brothers plan to rerecord selected Sims tracks with English lyrics. But true to their secretive nature, they won't say which ones.

One candidate might be "360," a particularly catchy groove that could have come straight off the pop charts. The song was written in a single night on an acoustic guitar, and the Brothers seem particularly proud of it.

The Simlish music has proven to be popular with fans, who want to be able to listen to it outside the game. For Bustin' Out, EA provided a double album's worth of tunes--complete with printable CD graphics, a case, and a smattering of songs from The Sims 2.

For The Sims 2 University, the recently released expansion pack, Kauker and his team wanted to tap a college radio vibe and so they looked for smaller acts on the cusp of hitting it big; the kind of bands called "emerging recording artists" in press releases. Among the 11 new tunes on the college rock station, listeners will be treated to performances by Dexter Freebish, Abra Moore, Charlotte Martin, Da Riffs, and Steadman.

Other than a one-off project with the Black Eyed Peas, which recorded Simlish versions of its songs for Urbz: Sims in the City, University represents a change in Maxis' approach to Sims music.

"University is the first time we're using real bands," Kauker said.

Each artist rerecorded one of their songs with new vocal tracks, replacing English lyrics with nonsensical Sim-speak. Simlish words don't have any real meaning, so the artists were free to come up with whatever sounded good, as long as English didn't seep in.

The result isn't that different from what bands like the Cocteau Twins and Vas already do. The idea is to transcend words and use the human voice to express pure emotion.

Charlotte Martin, whose song "Beautiful Life" finds its way onto the University soundtrack, took things a step further than some of the other artists. She didn't just sing gobbledygook, she made sure all the Simlish words were consistent with their counterparts in the English version.

"It still had the same meaning, I just had to write it in an alien language," Martin said.

In rewriting the song, Martin said it changed the way she thinks about lyrics, letting her come at her creation from a more technical standpoint, paying closer attention to syllables and rhythm.

Martin isn't a gamer--though she swears she's going to try The Sims 2--but she enjoys recording game music. Among other projects, she cowrote and recorded "Greater Lights," a song for the upcoming Xbox title Advent Rising. That project found her singing with a 70-piece orchestra, so Martin understands how serious developers are about the music in their games and she's enthusiastic about being part of it.

"Video games are certainly selling more than records, so they must be doing something right," Martin said, seemingly mulling over her alternatives if this whole pop star thing doesn't work out.

For songstress Abra Moore, whose song "Big Sky" was used in the game, singing in Simlish gave her a new perspective on her music. "It's like jazz for me; I just take to it like a duck to water," Moore said. "It was very liberating creatively."

However, Moore, who also speaks Italian and Spanish, said she took special care that none of her Simlish words ended up accidentally being curse words in foreign languages.

The experience made such an impression on Moore that she said she'd consider recording a song in Sim-like scat on a future album. She perceives the emotional lyrics, divorced of a specific meaning, in almost a spiritual light. She's fascinated that fans try to interpret the nonsensical lyrics. It represents the essence of human nature, Moore said, to take meaning from something that has no meaning.

Who knew The Sims was so deep?