The highlight of the stimulating "Young Lions" concert—a showcase for 16 rising stars—at New York's Kool Jazz Festival in June was a scampering trumpet duet that left the audience laughing and cheering. Actually, it involved only one trumpet, played by Wynton Marsalis. The sound of the other trumpet came tumbling forth from Bobby McFerrin's extraordinary vocal cords. For the 32-year-old New York native, singing is child's play in the best sense, a spontaneous and joyful form of creation. Elfin and puckish onstage, he ascends often into numerous falsetto voices and punctuates himself with sudden chirps and beeps. While Louis Armstrong's famous polysyllabic scatting was a form of improvised speech, McFerrin's, even more than Ella Fitzgerald's or Al Jarreau's, pays homage to instruments. In this debut album, using overdubs, he renders Bud Powell's bebop classic Hallucinations as a high-speed duet for "bass" and "trumpet." The point is less his startling mimicry than his musicianship: It's not just the slight buzz he imparts to the trumpet part that conjures up Dizzy Gillespie playing with a mute, it's the liveliness and intelligence of the solo itself. For all his scat genius, McFerrin still has much to learn. Though rich and warm, his normal baritone could handle lyrics more expressively. In the conventionally sung songs (seven of the 10 cuts), such as his own Jubilee and Van Morrison's Moondance, his special effects sometimes seem gratuitous. But McFerrin should endure. Originals usually do.