Love barbershop music.  It's normally performed by a quartet.
It's famous for it's ringing chords, produced by singing a combination of notes that are perfectly tuned.
usually sung by the tenor or baritone, except for an infrequent note or two to avoid awkward voice leading, 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,
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.
Ringing chords.
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 by the listener as a distinct tone, even though none of the voices are perceived as singing that tone. This effect occurs when the