While the air is clogged with the sound of Mill Avenue traffic zipping by, the lanky 24-year-old uses his PowerBook G4 to generate his own brand of noise pollution in the form of warbling high-pitched bleeps, punctuated by millions of drumbeats.
"I really dig this one; it's something I've been perfecting," says Rosen, frantically fiddling with the on-screen controls of a sound sequencing program, transforming the tempo and texture until the electronica ditty sounds like a Nintendo Entertainment-style jam with a bad case of ADD.
When asked to drop some science about his songs, Rosen fires off a string of techno-babble about programming environments, control patches, trigonometrical algorithms, and wave-forms, before describing how he draws inspiration from such artists as John Coltrane and Aphex Twin.
Welcome to the world of laptop-created e-music -- dubbed "laptronica" by some -- populated by experimental one-man acts such as Rosen who use their notebook computers and host of programs (with names like Reactor, Fruity Loops, and Max/MSP) to generate and manipulate different genres of electronica, from frenetic hardcore breakbeats to tripped-out ambient techno. Performers unload their music on fans using only a laptop and MIDI controller as the hardware, tweaking and transforming their songs as they stream out.
The nebulous subset possesses personalities and techniques as disparate as the kinds of music they create. There are the math-whiz-meets-music-nerd types like Rosen, who dabble in the technical aspects and music theory, while others play it by ear.
Scot McKenzie, co-owner of downtown art house .anti_space, says some laptop jocks are purists, using no samples, while others use the sound bites to flavor their funk. There's even dancing to be had as performers often groove to the beat while laying down the sounds of the underground.
Although the laptop scene has been lighting up such Left Coast cities as Seattle and San Francisco for years, the Valley is still getting its feet wet, with notables like Terminal 11 and Back Ted N-Ted participating in this weekend's Laptop Battle at .anti_space.
"Some of the artists here are abso-fucking-lutely just mind-blowingly good, and really should be signed to labels," McKenzie says. "So hopefully this will get them a little bit of exposure."
Rosen, who performs as "Alphabot 23," and seven other laptop jocks will go head-to-head in a single-elimination tourney similar to a DJ battle, each getting three minutes in each round to kick out the jams. Judges will rate participants on creativity, musicianship, performance, and crowd reaction, with the winner pocketing a phat gift certificate from Swell Records and tickets to see Brit beat-masters Autechre perform.
But Rosen, who's been performing for about a year, predicts he'll probably be making an early exit. In fact, he's not only expecting to get schooled by the veterans, he'll be upset if he isn't.
"I hope I get destroyed, because it'll mean there's a strong laptop community here," Rosen says. "I really want everyone to do crazy and creative shit, 'cause I'd be disappointed if people just go out, play their shit, and don't do anything new or innovative."