THE URBS IN CONCERT

It does not at first seem the kind of music that would appeal to young people - or at least, an older person's notion of young people. Simple lyric ballads, sung without stagey mannerisms or ironic cool. ``They don't have the icy pop quality Tracy Chapman has,'' observes Richard Meyer of Fast Folk magazine.

Yet the young people in the audience were the ones most impressed. ``I would buy every one of their records,'' said Michelle Diffenderfer of Chicago.

It was Tarmo and Thomas Urb's first American concert, given to a small gathering at the Desisto School in Stockbridge, Mass. (A group from the school met the singers in Estonia while traveling with a production of ``Hair.'')

Their style is intimate and familiar, more suited to a cabaret than an amphitheater. The songs ranged from translations of their Estonian allegories, affectingly innocent, to a nifty Estonian version of Simon and Garfunkel's ``Homeward Bound.''

Thomas has the better singing voice, richer and more expressive. Tarmo has a stage presence that is nothing short of riveting. ``When their voices work together, it's amazing,'' says Catherine Wakeford, another student at Desisto. ``It gives you the chills.''

There's a purity to their music that makes it hard to tag. People mentioned such names as Simon and Garfunkel and Don McLean. ``This is real folk art that Nashville is not,'' said Arthur Collins, a retired English professor.

Said Ms. Diffenderfer, ``They are so original, they don't remind me of anyone.''