"Traditional Sculpture from Upper Volta" at the Museum of African Art, 316-332 A St. NE., is an exhibition both frustrating and splendid.

Though the finest of these objects - these carved and painted maks, staffs and statuettes - are exceptionally beautiful, the awe we feel before them inevitably is hollow. Our ignorance still veils their majesty, their magic. We do not know enough to see more than a fraction of the meanings and the powers they contain.

A sculpture from West Africa steeped in the traditions of the Bobo or the Bwa, who had never heard of Valley Forge, might be just as mystified by a painting of George Washington. Why, he might well wonder, is that whitehaired man standing in a boat?

These flutes, spoons, and bronze pendants, these carved and painted masks raise - but do not answer - comparable questions. The masks are holy objects. They were not carved to please the eye of a collector. Unless we know their secrets, their seasons, songs and dances, we can only guess at the spirits they summon.

Kurumba masks, the catalogue informs us, are painted with the "greatest secrecy." "At the time of the sacrifice initiating use of a new mask, it is given a name and henceforth is considered to have a life of its own . . . On the 'death' of a mask, when it has become damaged beyond further use, it receives sacrifices and a proper burial, like a man." But here one sits in a glass case, unnamed, unsung, mute.

Those who know its secrets in many instances have been unwilling to disclose them. To know that in Upper Volta butterflies swarm after the first wet-season rains to understand a little, but not very much, about the huge winged mask that is here on display. Why is it painted red, white and black? Why are there small carved birds spinning on its edges? What does this object mean?

Buffalo, chameleons, hornbills, snakes and other living things are often represented in the carvings on display. "Specific attributes of character or temperament may be attributed to certain ones," writes Norman Skougstad in the catalogue: "Stupidity to the hyena, for example; strength to the bushcow, cleverness to the hare, and so on . . . The use of animal motifs should be interpreted with care, however, as specific references may vary from one group to the next." Many of these objects are written in a language that we cannot read.

To think of them as art, to study them as sculpture, to compare the helms of Bobo helmets with those made by the Greeks, to measure Lobi statues against those of Western Europe, is to misapprehend them. These once were living objects; seen in a museum, they seem beautiful but dead.

Despite the slides displayed here, the labels and recordings, that situation may never be corrected.

"Only one ethnographic study," writes Skougstad, "discusses Voltaic sculpture in any depth." Many more are needed, but it may too late.

Today in rural Africa the old secrets are being lost; the old techniques are dying. "Traditional jewelry," he writes "has become passe with the increasing popularity of glass and plastic; door and doorlocks once carved of wood are being replaced by modern metal hardware; carved and decorated chairs may become less prestigious than imported folding canvas types . . . Because objects are often discarded, collected or sold without documentation, it is becoming increasingly difficult to determine local style variations or particular uses."

The Gurunsi flutes here are extraordinary sculptures, but what are the sacred tunes they were carved to play? That Nuna spoon is beautiful, but what function dit it serve" The beauty of this show is the beauty of a ghost.

The exhibition originally was organized by the African-American Institute of New York. It features works from the collection of Thomas G.B. Wheelock, though for the Washington display his holdings have been augmented by loans from the Baltimore Museum or Art, the University of Pennsylvania Museum, and private collections. Forty objects from the African Museum's collection also are on view. The show closes Sept. 10. CAPTION: Picture 1, Bobo helmut mask; Picture 2, Male and female Lobi statues