Some takes time to get to know. Some just stays unforthcoming, a mystery. The theme of sound in art is hot these days. The Tang, like the Whitney, covers a stretch of the postwar waterfront, giving preference to visual work that has an implied or actual aural component. Pop kicks things off with a 1961 Warhol silkscreen painting of an old-fashioned telephone and a set of 1962 phonograph records in which American baseball heroes explain what makes them tick.
Performance plays a big, though sometimes passive, role.
A set of sensational-looking costumes bristling with yarn, metal and wood, by the Chicago artist Nick Cave, stand mute and commanding near the front of the show. When he wears them in performances, the movement of their dense material is miked and amplified. And if you pick up the receivers on the pay telephones in the museum lobby, you'll be treated to one of five three-minute playlets, courtesy of the Actors Theater in Louisville, Ky. Sound, particularly speech, comes with its share of problems. The voice you hear when you walk into Rafe Churchill's replica of his bathroom is a recording of the artist repeating daily exercises meant to correct his stutter. A few ''pure'' sound pieces are included, notably one by Jeff Talman based on ambient noise in the museum lobby, along with work that fits into no ready category.