Maybe not everyone knows that…
Barbershop music is a form of a cappella music very popular throughout the United States, and it is characterized by consonant four-part chords for every melody note in a predominantly homophonic texture. The barbershop style of music was first associated with black southern quartets of the late 19th century.
Barbershop music is typically performed by a quartet of men with the following voices: tenor, tenor, baritone, and bass. Women also sing barbershop music, but their quartets are referred to as “Sweet Adelines.”
The expression “barbershop music” may date from a time when American barbershops were social and musical centers for men, where clients waiting to be shaved could start improvised performances.
The main characteristic of this style is the “ringing” chord, which is a name for one particular acoustical effect, also referred to as “the fifth voice,” or “the overtone.” If the four voices sing properly tuned chords on the right combination of notes, the frequencies and harmonics in their sounds combine to create an overtone, which sounds like an extra note.
Even if traditionally barbershop music groups were all-men or all-women, in the late 20th century, mixed groups were also formed.