Barbershop music in tags or codas, or when some appropriate embellishment can be created. One characteristic feature of barbershop harmony is the use of what is known as "snakes" and "swipes." This is when a chord is altered by a change in one or more non-melodic voices. Occasional passages may be sung by fewer than four voice parts. Barbershop music is generally performed by either a barbershop quartet, a group of four singers with one on each vocal part, or a barbershop chorus, which closely resembles a choir with the notable exception of the genre of music. According to the Barbershop Harmony
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".