Barbershop music countertenor, the baritone resembles the Heldentenor or lyric baritone in range and a tenor in tessitura, and the lead generally corresponds to the tenor of classical repertoire, with some singers possessing a tessitura more similar to that of a high baritone. Barbershop singing is performed both by men's and women's groups; the elements of the barbershop style and the names of the voice parts are the same for both. The defining characteristic of the barbershop style is the "ringing" chord, one in which certain overtones of the four voices reinforce each other, sometimes so strongly that the overtone is perceived
Barbershop music recording industry their performances were recorded and sold. Early standards included songs such as "Shine On, Harvest Moon", "Hello, Ma Baby", and "Sweet Adeline". Johnson noted in the 1920s how the genre had already crossed racial barriers. Barbershop music was very popular between 1900 and 1919, and some of the most popular quartets were the Haydn Quartet, the American Quartet, and the Peerless Quartet. Modern barbershop quartets often costume themselves in gaudy versions of the vaudeville dress of this time, with boaters and vertically striped vests. Composer and pianist Scott Joplin incorporated a barbershop quartet into his 1911 opera "Treemonisha".