MILT HINTON's nicknames have changed over 72 years. He was Sporty in his Chicago teenhood. He was Fump in his bass-slapping years with the Cab Calloway band. And in New York's recording studio empire, he was The Judge who kept everyone honest.

The bassist has been a firsthand witness to the changes in a society that once tolerated lynching, that prohibited black and white musicians from playing together, that consistently overlooked the dominant black contributions to America's classical music, jazz.

As a virtuoso, Hinton's been known not just for the time he's kept, but for the company as well: Lionel Hampton, Billie Holiday, Jackie Gleason, Mahalia Jackson, Barbra Streisand, Aretha Franklin, Bing Crosby, Eddie Fisher. He's learned from masters and taught students, and stretched the role of his traditionally undervalued and often misunderstood instrument. When President Reagan honored Hampton last year on the South Lawn, it was Hinton who provided the bottom.

"We're proving what we believed in all the time," Hinton said then, in a soft voice that still carried traces of his Mississippi roots. "We know the dues that we paid. Now we can stand tall and walk in the White House. I've been every place in the world you can name. You don't have to speak the language. We speak our own language--American jazz."

Hinton will provide the bottom again on Thursday when he joins vibes player Hampton, drummer Louie Bellson and pianist Teddy Wilson on the Wolf Trap stage. He'll be celebrating more than a half-century in the music he started making in 1931, supporting violinist Eddie South. Hinton's not a leader, but a sterling example who's been content to let his fingers do the walking and the talking. He's not even that well-known outside music circles, but his upright bass has provided essential support to hundreds of recording artists, as well as continuing the strategy of bass innovation and redefinition that started with Jimmy Blanton and Oscar Pettiford. "I just fell in line," Hinton says modestly, "tried to step in behind them. And I've been able to survive by so doing. When you call a man a genius, you're not giving him credit for his hard work."

Dressed in a somber gray suit, the dapper Hinton looks very much the teacher and administrator that he has been (at Hunter College and as former cochairman of the National Endowment for the Arts jazz panel). In his long career, he's watched America turn inside out; even his instrument has been redefined through better construction and the introduction of steel strings and amplification.

But the surrounding social and political events have been important, too, and Hinton has become something of a historian and collector of jazz memorabilia. He's been documenting those changes with photos for more than 50 years and has pushed hard for oral history projects like those run by the Smithsonian and the Jazz Institute at Rutgers.

"It's so important to get the old-timers like me before we go, to find out what things were like in my time, telling it the way we saw it," he says fervently. "We should know our heritage. Take Louis Armstrong, a man who was born in the South 80 years ago, an orphan. What were his chances of becoming famous? And yet he's a man who touched the world. You can go in the middle of the jungle and you'll find Louis Armstrong and Coca-Cola."

Hinton is concerned that young people understand the milieu in which jazz grew, particularly the strictly enforced segregation between black and white musicians. "I'm only third generation from slavery," Hinton points out, "and my grandmother, a slave to Jefferson Davis' father, lived till I was a grown man in Cab Calloway's band."

As a youngster in Vicksburg, Miss., Hinton remembered "seeing a crowd, people all around, men shooting, a big barrel of gasoline on the ground and a man is on fire, like a piece of bacon with a wire rope around his neck. In Vicksburg, when you lynched a nigger, you cut the tree down and painted the stump red. I walked to school past that stump every day, but I couldn't understand what was happening."

His family moved to Chicago over a period of years, women and children coming north to join the men who had migrated to work in the stockyards for "$20 a week and all the meat they could carry home." In the Windy City, Hinton first met Hampton as a fellow student in the famed high school band of Major N. Clark Smith.

Hinton was initially a violinist, though he also played the 6-foot bass saxophone. "I loved everything big," he laughs. "If it wasn't big, I didn't want to play it." Chicago was where he picked up his first nickname, Sporty. "I never cared much for Milton 'cause I got in such trouble," he laughs, now. "Can you imagine living in a black neighborhood and being named Milton and playing a violin? Man, I had to fight my way through school!"

Hinton switched to bass in 1929 after the arrival of "The Jazz Singer." Talkies wiped out the theater orchestras that previously had accompanied the silents; that had been the only refuge for black violinists. He also was inspired by early morning encounters as a paperboy with well-heeled musicians just heading home: "I felt I knew as much music as them."

He began to carve out a reputation around Chicago and, in 1936, when Calloway headed back East from a California tour looking for a bass player, they connected . . . and stayed together for the next 15 years. "I had never played with a full brass section before," Hinton recalled, "and when that band hit, I practically picked up my bass and ran. I'd never heard such a full sound before!" Calloway gave him his second nickname--Fump--based on the thumping tone coming from the upright bass.

The bassist recalls the era when black and white musicians couldn't play on the same stage. "We always respected each other, but those were the rules of the land. I remember Joe Venuti and Eddie Lang putting on cork to go up to Harlem so they could sit on the bandstand without being given a hard time. The black musicians would be dying laughing." There were sober times, as well, like when the band would make "a bushelbasket of money and we'd have to get on the bus and ride 300 miles before we could get served a sandwich." It's that kind of social background Hinton's been documenting with photographs for five decades.

Already the first black bass player to graduate from college (Northwestern), Hinton became the Jackie Robinson of the recording studio as well. Although he'd been active on many jazz records and records geared to Southern blacks, Hinton and other top black musicians were systematically cut out of lucrative session work. The American bandstand had been integrated by Benny Goodman and Hampton and Teddy Wilson in 1936, but though "the rules began to be changed and relaxed," the studios kept up their walls. "It took a little longer for us there, but I think you have to take what you get and make what you want."

In the early '50s, soon after the dissolution of the Calloway band, the bassist ran into a onetime struggling comedian who remembered Hinton's kindnesses and friendship from earlier years on the club circuit "when he also couldn't get arrested. We worked for tips and took care of each other." A suddenly successful Jackie Gleason bullied the studio chiefs and pushed Hinton into a "Music for Lovers" session; within 10 years, working three long sessions a day, Hinton had made more records than any other bass player alive. With the general demise of session work, "that record's got a good chance of holding up," he says proudly.

The studio was also where he picked up his last nickname, The Judge. "I had a tradition for being punctual and on time. Long before the sessions would start, I'd be there tuning up and the other cats would walk in and say, 'Well, the Judge is here, good morning Judge.' I used to have it on my letterhead: "The Judge sentences you to 30 days of listening to good music!' "

The versatile Hinton backed hundreds of recordings artists: Mahalia Jackson, Errol Garner, Barbra Streisand, Aretha Franklin, Dinah Shore, Johnny Mathis, Bing Crosby (including the crooner's last session). "I did every Eddie Fisher record, when he and Debbie Reynolds used to run up and down the halls with their big dogs," he says with a grateful laugh. "Eddie paid my mortgage with overtime." Like a batting champ knowing his league's pitchers, Hinton got to know the predilections of singers and instrumentalists. "Music is a service. If you take a job, you play whatever's required. You're supposed to make that band sound good."

Hinton also became a part of the New York Rhythm Section, an intuitive studio group that was a great help to arrangers who couldn't really arrange. He worked in Dick Cavett's studio band, taught jazz at Hunter College and continues to play both sessions and concerts. It's a long way, he says, from back-of-the-bus status, when an unamplified bassist used to have to "get out over 16 instruments in a mile-long ballroom," when the instrument was strictly a rhythm machine.

"You sit back there, unglorified and playing supportively. You play with all the great names under the sun, but nobody really knows you. But the music doesn't stand without it. Bass means bottom, and you got to have bottom for the building to stand."