Barry Hemphill took up the trumpet at the age of 4, but he had to quit when his baby teeth fell out. He resumed trumpeting at age 6.

Hemphill's music making comes naturally.

What else would you expect from a man whose father played first trumpet for years with Duke Ellington's band?

"Billie Holiday fed me fried chicken and acted as my babysitter, and the Mills Brothers played catch with me as a youngster - literally tossing me through the air to one another like a ball," he remembers.

Although his late father quit trumpet peting in 1951, Hemphill has kept on playing the horn, studying, singing conducting and making professional music for most of his 31 years.

His appointment as mucis director of the Arlington Metropolitan Chorus was announced recently. He will hold the post in addition to his career work with the U.S. Army Chorus in nearby Fort Myer, where he has served as assistant conductor for the past nine years.

H egot into professional conducting in a roundabout way, he explained during an interview in his Alexandria home.

After learning the trumpet from his father, he branched out musically.

"I was singing professionally, making money at it, at age 13 in churches and choirs," he said. He also played the baritone horn in his junior high school orchestra, played percussion in high school and started conducting about the same time.

"After high school, I showed up one day at the Manhattan School of Music with my baritone horn," Hemphill said. "I had stopped playing trumpet a year before to concentrate on the horn, just to pass this audition."

The school didn't accept his band instrument for study, though, and school authorities asked him what else he could audition for.

"I couldn't go for trumpet at that time, since my year of solid study on the horn had ruined my trumpeting Voice? No way. Piano? Forget it! Finally they mentioned theory. Hmm, I said. Maybe. I could try theory," he recalls.

Brooklyn born and raised, Hemphill spent five years at Manhattan School of Music. He then took a tour abroad as assistant conductor with the New York Scola Cantorum under Hugh Ross. Toscanini's chorus director.

Loosing his student status, however, led to official greetings from Uncle Sam, so upon his return to the United States in 1968 he entered the Army. He's been there ever since and, in addition to assisting in conducting the Army chorus, he conducts the Army chamber singers and appears as soloist with the Army band and chorus.

In 1972, Hemphill sand the role of Andy in a Wolf Trap performance of Scott Joplin's jazz opera, "Treemonisha."

As music director of the recently reorganized Arlington Metropolitan Chorus, he plans three concerts in 1977-78, starting with a Christmas program on Dec. 11 featuring Randall Thompson's "The Peaceable Kingdom" and Danie Pinkham's "Christmas Cantata." He has also scheduled auditions in Arlington singing larger works." (Call 558-2161 for more information.)