Barbership quartets are upbeat about a resurgence of interest in their music, and they're singing out loud and clear on the 50th anniversary of their international society. More than 10,000 people have registered for this week's international convention of the Society for the Preservation and Encouragement of Barbershop Quartet Singing in America. ``I think we are gaining some respect again across the country,'' said James Warner, a Memphis attorney and international president of the 38,000-member organization. ``We are developing programs for young men in some high schools and it's found increasing acceptance,'' he said. ``We're not using it as a recruitment device, but as an attempt to reach out to young men in that area,'' he said. Barbershop quartets, which popped up mainly on the East Coast at the turn of the century and were popular during the vaudeville era, use four-part harmonies to carry tunes. The lead singer carries the melody. A tenor harmonizes and a baritone and a bass carry the lower chords. There is no instrumental accompaniment. Competition begins Thursday with 51 quartets battling for five finalist positions. Sixteen choruses comprised of 50 men also will vie for five finalist positions. The finals are scheduled for Saturday with one gold, one silver and three bronze medals being awarded in each category and the gold medal winner becoming the international champion. ``This is the Olympics of barbershop singing and all of them have had to battle on the local level to get here,'' Warner said. ``It will be a tough competition because there is a lot of prestige that goes with the medals.'' On Wednesday, crooners warmed up, gathering in hotel rooms and hallways to belt out such barbershop classics as ``Sweet Adeline.'' Greg Zinke, 27, a member of the Northeast Extension of Pemberton, N.J., said he began singing in a quartet after being around his father's group. Zinke, who works in a tool and die shop in High Bridge, N.J., said he opted for barbershop quartet singing instead of rock 'n roll because of the selection of clean, simple old songs. ``You don't have to be a fantastic singer to do this. I think that's what makes it so nice for the guy off the street who admires the music. He can come sing it, too,'' he said. For a long time, barbershop quartet singing was in a decline, as the vaudeville era came to an end with the advent of motion pictures and other forms of music after World War I. In 1938, Owen C. Cash, a tax attorney in Tulsa, Okla., and Rupert Hall, another Tulsa businessman, formed the society to preserve the old music. Their group helped revive interest, and there are now 2,000 quartets and 800 choruses divided into 16 regions in the United States and Canada and other groups in England, Sweden, West Germany, Holland and New Zealand. Doctors, lawyers, researchers, plumbers, electricians are among the barbershop quartet singers, but ironically, few barbers are members of the organization, Warner said. ``It' easy to sing and it's portable,'' said 35-year-old Roger Payne of Manhattan. ``All you have to have is your pitch pipe and three other guys and you don't have to call anybody to move your piano. It interacts with the audience in a real entertainment-kind of way.''