The National Symphony Orchesta's concert Friday night at Wolf Trap began merrily when assistant concertmaster Bok-Soo Kim launched the musicians into "Happy Birthday" as guest conductor Franz Allers strode on stage. The concert celebrated Allers' 80th birthday, actually Aug. 6.

Smiles were all around as the musicians returned some of the cheer the Tony Award-winning conductor had given others for many years. Allers, the NSO and the Oratorio Society of Washington (which began its 25th season with Friday's performance) were joined by soprano Marvis Martin and bass-baritone Donnie Ray Albert for a program of classic show tunes by Cole Porter, Jerome Kern and George Gershwin.

A vigorous reading of Gould's "American Salute" -- a medley of folk songs -- opened the concert. A line from Kern sums up the remainder of the program: "The music is sweet, the words are true."

Albert's mellifluous voice wrapped itself easily around the immortal "Ol' Man River" and "Make Believe" and especially dominated the selections from "Porgy and Bess." Martin's rich soprano sparkled as she gracefully sang her duets and solos. The audience's standing ovation and shouts persuaded the singers and musicians to reprise the last Gershwin selection as an encore. The evening was both a musical and a theatrical treat.