The Barbershop Harmony Society is devoted to promoting, preserving, and enjoying a special form of harmony known as barbershop. But what makes a particular song or arrangement “barbershop-able”? What’s the difference between barbershop and doo-wop, jazz, madrigal, and other a capella music?

Technically speaking, barbershop harmony is a style of unacompanied singing with three voices harmonizing to the melody. The lead usually sings the melody, with the tenor harmonizing above the lead. The bass sings the lowest harmonizing notes and the baritone provides in-between notes, either above or below the lead to make chords (specifically dominant-type or “barbershop” sevenths) that give barbershop its distinctive “full” sound.

Probably the most distinctive facet of barbershop harmony is the phenomenon known as expanded sound. It is created when the harmonies in the individually-sung tones reinforce each other to produce audible overtones or undertones. Barbershoppers call this “ringing a chord.” Singing in a quartet or chorus and creating that “fifth voice” is one of the most thrilling musical sensations you will ever experience — one that often gives singers goosebumps.

— Adapted from the 2000 Santa Fe Harmonizers annual show program.