A battered, white step-truck rattled to a stop near the corner of Fourth Street and Martin Luthur King Jr. Avenue in Southeast Washington. For a moment it sat quietly in the noon sun as newly fallen leaves crackled in their race with a breeze.

Then, suddenly there was a rude blast of sound:

"Get your back up off the wall, dance, come on!" a recorded voice shouted in a syncopated rhythm that bolted from a storm of multi-percussion beats, synthesized beeps, explosions and quick-jabbing R&B horn lines.

The music blared from tinny speakers, blanketing the area's littered streets, its neat and not-so-neat little houses and storefront businesses. In the process, hundreds of students from nearby Ballou Senior High School were drawn to the step-truck that sells cookies, sodas and ice-cream from a window behind bars. Some danced, doing the "Happy Feet," to the beat. Many just nodded in time as they munched on 45-cent chili dogs and sipped soda.

"Michael Jackson is all right, but this is the best," said Marcus Johnson, 16, who was within earshot of a parked car that, too, was loud with the same type of music pouring from its cassette tape deck: "I feel like bustin' loose, bustin' loose . . . "

The music seems to be everywhere: sang, played and carried in oversized, shoulder-mounted tape players and radios in every quadrant of the nation's capital. The music, with its broken melody lines and chants urging one to "rock your butt, y'all," can be heard at metro stops, city parks and playgrounds where school girls jump rope to its beat.

It's "go-go" music, and it is the District's own -- rough, aggressive, urban and black.

With its loud funky bass lines and harsh harmonies, this music sketches a portrait of the District's black community in which the seeing is in the ears. Much like reggae, a music born of the Caribbean ghettos, the D.C. sound has become a sociology that rocks, its creators say.

"Our sound is very vicious, cocky," said Robert Reed, the 27-year-old singer and keyboard player for "Trouble Funk," one of the most successful of the "go-go" groups. "It's driving, and demands that you be part of it."

Home-grown combos such as Rare Essence, Experience Unlimited, Trouble Funk, Reds and the Boys, the Pump Blenders, and Hot, Cold Sweat, and Chuck Brown and the Soul Searchers have recently been enjoying unprecedented popularity.

For years, the D.C. sound has been heard in heaping audible doses in local nightclubs, rented halls and in Landover's mammoth Capital Centre. Even the District Police Department Side-by-Side Band, a youth-oriented combo, plays "OO La La," a go-go song.

But now, say the go-go promoters, the music is ready to woo national and international audiences much like Motown and the sound of Philadelphia did in decades past. Trouble Funk is preparing for a six-week tour of Europe next month and is also exploring offers to take its live act to West Africa, according to its management.

Chuck Brown just grins, flashing a glint of gold that frames one of his chalk-white front teeth, when he hears that go-go music is really on the go, this time. The 49-year-old ex-boxer, ex-bricklayer and ex-convict is credited with being the godfather of the D.C. sound.

Several months ago, Brown had one of the biggest hits of his 25-year career with the materialistic "We Need Some Money," that chants:

"MasterCard, Visa, American Express, I ain't got nothin' against no credit cards, but cash is the best."

"Money?" the word is uttered in Brown's rich, coarse-edged voice, earned the old-fashioned way: countless nights of singing his lungs out in smoky night spots on the winding road to today's moderate success. "The inspiration came from my personal experience. The last five years I've been broke, the whole band's been broke."

Brown came to Washington at age 5 with his mother from Gaston, N.C. Soon after he began playing the organ at Mount Zion Holiest Church of God, he formed the Soul Searchers in 1968. They quickly became local favorites playing the cabaret scene. And there were hits, the group's biggest came in 1979 with "Bustin' Loose," its structure as much go-go then as it is now.

"You get that African root feel with that percussion," Brown explained. "You might drop a little music, drop some lyrics; you drop some audience participation, some chants and it became a style after all the other local bands adapted to it."

But financial success eluded him and his band. "We discovered the fact -- hey, we ain't got no money."

Yet, there was never despair, he said. And the lyrics of "We Need Some Money," reflect the upbeat, bouncing optimism the black community musters in hard times, he said.

"Our music has developed a very positive vibe," he said. "A positive vibe that's love."

Brown's tune placed on the national black music charts and has been heard from coast to coast. When the single appeared in local record stores late this spring, store managers said their young, predominantly black customers had been asking for the record for almost a month.

"You could be holding up copies and people would come in and snatch it out of your hands," said Alice Dell, a cashier at The Wiz, a downtown record store. "It was wild."

In a day's time, Dell said, the store sold at least 1,000 copies of Brown's record. An estimated 150,000 copies have already been sold, according to his record company.

But some critics of the music don't believe the music -- in its present form -- will ever gain a large national following. Nelson George, writing in a recent issue of Billboard magazine, said one reason for go-go's relative obscurity is "that it's a very difficult style to capture properly on vinyl."

John (Turk) Edwards, a disc jockey with WDJY, said the major markets still aren't ready for the sound.

"I don't really think it's really palpable to everyone in the country," he said. "It's such an unique sound."

Spawned in the streets in and around the city's housing projects more than a decade and a half ago, primitive "go-go" music was first heard on pot-and-pan-sounding drums and cheap electric guitars.

"The sound was created out of inefficient instruments, just anything they could do to make an instrument," said Maxx Kidd, the flamboyant co-president and general manager of T.T.E.D. records, the local independent record company that handles most of the city's go-go bands, including Chuck Brown and the Soul Searchers.

"When I first hooked up with Trouble Funk , the drummer was playing on some bad stuff," Kidd recalled with a wiry smile. "I asked him if he was trying to get a particular sound out of those toy cymbals. He said, 'naw, we just didn't have enough money to buy anything better.' "

Most young musicians growing up in the District couldn't afford the expensive instruments required to produce a crisp, professional sound, said Kidd. And few, he added, knew very much about music.

Brown, for example, said his first guitar was made for him by a fellow inmate at Lorton for five cartons of cigarettes.

Johnny Mercer, a former musician and attorney for Kidd's company, said it was what these bands lacked materially that most influenced their sound artistically.

Basically, most of the District's young black bands started by attempting to play the top 40 tunes heard on soul radio stations, he said. But instead of learning a lot of songs that would be difficult for novice musicians, the go-go pioneers simply stretched out a song, pleasing audiences with a groove to dance to and an opportunity to be part of the show by interacting with the music makers.

"They would improvise on that extension, and go heavy on the rhythm parts," Mercer said.

The audience would respond with chants, many of which were merely sayings popular in the streets at the time, he explained.

The result was a musical form that for the most part replaced lyrics with call and responses between the musicians and the audience. The theme of the songs seldom deviated from salvation through frenzied partying.

When Experience Unlimited urges its dancing listeners to do the "EU Freeze," it reminds the audience that money is frozen, jobs are frozen and the world is a very cold place.

"There's a message in what they are singing about," said Darrell West, a 17-year-old District high school senior who wants to be a computer trouble-shooter. " . . . it's all related to what's happening out here."

But Ron Clark, executive director of RAP Inc., a Disrict-based antidrug program, said he is not pleased by some of the messages the go-go bands are sending out. Last summer, he said, one of the groups was glorifying in its lyrics the use of "Lovely," better known as PCP, a dangerous hallucinogen.

RAP countered by persuading Experience Unlimited to record "Luv Boat," a go-go song that warns: "Don't take another tote of that Luv Boat/ Don't take another trip on that boat."

"We've had some success with that," Clark said.

Kidd, 43, is pleased. Go-go music as the Great Communicator helps to fuel his vision that someday the D.C. sound will conquer the planet.

"It's going to be bigger than disco," proclaimed Kidd, dressed in faded jeans and a flak jacket topped with four stars on each shoulder. "There's going to be go-go clothes, go-go cars, go-go . . . everything!"

"That funky go-go sound is coming to your town," chanted Kidd as he eased into his late-model Mercedes sedan. "Watch out y'all, here comes the go-go!