Ever walk into a barbershop and just listen to the music they've got playing in there? Sounds like its own thing. I'm always curious about it when I go and get my hair cut.
There is a whole genre of music called Barbershop vocal harmony.  It is a cappella style consisting of four parts.
A whole genre of music.. Who would have thought. Wonder why that came about. Do you know the origins of it?
It started in the 1930's during the barbershop revival.
Can you get anymore specific? It's still kind of a cloudy picture
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 Society (BHS), "Barbershop music features songs with understandable lyrics and easily singable melodies, whose tones clearly define a tonal center and imply major and minor chords and barbershop (dominant and secondary dominant) seventh chords that resolve primarily around the circle of fifths, while making frequent use of other resolutions." Slower barbershop songs
Barbershop quartet
A barbershop quartet is a group of four singers who sing music in the barbershop genre of singing, which uses four-part harmony without accompaniment by any instruments such as piano, a style called a cappella. It consists of a lead, the vocal part which generally carries the tune/melody; a bass, the part which provides the bass line to the melody; a tenor, the part which harmonizes above the lead; and a baritone, the part that completes the chord with the note not being