Robert Cannon likes to triple jump in silence. When the nightly fireworks resounded at the adjacent World's Fair tonight, Cannon was distracted enough to stop and watch. Then he produced his own fireworks, a winning leap of 55 feet 3/4 inches on the final jump of the competition at theTAC/USA Outdoor Track and Field Championships.

Willie Banks likes to jump amid crowd noise. The man who set an American record of 57-7 1/2 in this meet a year ago induced rhythmic clapping from the 2,000 fans tonight, but a dead spot on the runway limited his performance to a third-place 54-10 1/4.

Just as disappointed by the result was University of Tennessee graduate Paul Jordan, whose 54-10 3/4 led from early in the three-hour struggle until Cannon topped it. Usually, the leader after the trials gets to jump last, but officials, instead, mandated tonight that they would maintain their earlier order through the finals, regardless of performance.

"Distractions bother me, but the fireworks were kind of a nice backdrop, so I stopped and watched," Cannon said after his first national outdoor title. "I wasn't happy that people were leaving, but triple jumpers learn to expect that. We only get much respect in the Olympic Trials or in Europe."

"The best part of my jump is the last phase, and right where I took off they have the pole vault hole in the center," Banks said. "It makes for a different surface and they wouldn't let us test it. I couldn't even figure it out until the fourth jump. It's typical of what people seem to think of the triple jump."

Cannon's performance was the shortest winning jump since 1975.

In the other men's championship decided today, Jim Heiring won the 20-kilometer walk by more than two minutes in 1 hour 30 minutes 21.8 seconds. It was an ordeal, considering the up-and-down course, 90-degree heat and 95 percent humidity, but it was rewarding for Heiring, since it gave him a berth on the U.S. team for the dual meet with the Soviet Union in Indianapolis July 2-3.

Heiring was disqualified during last year's meet in the Soviet Union and was beaten by that country's best, Yevgeny Yevsyukov, in Oslo a month ago, although he did score a rare American success over the other Soviet entry.

A Stanford Track Club quartet of Evonne Hannus, Regina Jacobs (2:03.1), June Griffith and Tami Essington took more than nine seconds off the meet record in winning the 1,600-meter relay, one of three women's finals, in 8:22.26. Kim Schnurpfeil of Stanford completed an NCAA-TAC double by taking the 10,000 meters in 33:25.88 and Susan Liers-Westerfield retained her 5,000-meter walk title in 24:56.6.

Qualifying in other events was scheduled from 10 a.m. to 9 p.m., but The Athletics Congress tightened entry standards this year and many of the trials were canceled for lack of entries, leaving gaps in the program.

Carl Lewis scared off enough long-jump foes to negate trial activity, then cruised through his 100-meter quarterfinal in 10.23. Lewis' bid for a second straight double in those events was enhanced when NCAA champion Stanley Floyd withdrew from the 100 because of a hamstring pull.

Withdrawals decimated what had shaped up as a great 800-meter competition, with Don Paige's bone spur and Alberto Juantorena's lack of conditioning prompting both to scratch.

James Robinson, bidding for a fifth straight 800 title, advanced eased-up in 1:49.40. Also moving into Saturday's semifinals were Brian McNelis of Georgetown, 1:50.81, and Sandy Chapman, the Coolidge High product who attends Mount San Antonio (Calif.) Junior College, 1:48.26. Veteran Fred Sowerby of D.C. International and Ray Brown of Virginia were eliminated.

Greg Foster, the heir apparent to Renaldo Nehemiah's high hurdles crown, was a late dropout from that event, having struggled in vain against walking pneumonia for the past two weeks.

Mark Fricker, an Oregon State junior who was third in the NCAA meet, set a track record of 3:38.96 in the 1,500-meter semifinals. Steve Scott, 3:39.99, and Sydney Maree, 3:40.54, took more leisurely paths into Sunday's final.

Billy Olson, America's best pole vaulter, needed three tries to clear 17-4 1/2 and advance to Sunday's final. Among the missing, in tricky wind conditions, were Earl Bell and Maryland's Joe Petrillo.

Henry Marsh and John Gregorek followed the same route to Sunday's steeplechase final, running far behind in separate semis and then closing quickly to easily earn necessary places in the first five.

Alice Jackson of D.C. International ran a lifetime best of 52.72 in winning her 400-meter quarterfinal. Cathy Rattray, the Tennessee sophomore out of Bethesda-Chevy Chase High, advanced in 53.17 and Roberta Belle of D.C. International barely gained a semifinal berth in 53.85.

Cliff Wiley, the defending champion from Baltimore, won his 400-meter quarterfinal in 46.05, but complained that he was bothered by the heat seething upward from the Tartan track.