High Quality Content by WIKIPEDIA articles! Vocal Spectrum is a barbershop quartet from St. Charles, Missouri. In 2004, Vocal Spectrum won the Barbershop Harmony Society's International Collegiate Quartet Contest, and on July 8, 2006, they became International Champions, winning the society's International Quartet Contest. A distinctive factor of the quartet is the tenor's incredibly high note range, featured in many of the group's recordings and live shows. The quartet's run for the title is featured in the 2009 feature documentary American Harmony.