A cappella music is music where people sing without instruments.
In a choir, there are up to 5 parts: soprano, alto, tenor, baritone, and bass. A cappella can also have those 5 parts. A difference is with percussion. With musical instruments, percussion is done with musical instruments that you hit, such as drums. In an a cappella performance, a person makes the percussion sound. For a beatbox performance, performers make sounds like electric drums, synthesizer and electric guitar. Another part of percussion in a cappella performance is making classical drum sounds for tapping the beat.
A barbershop group has 4 people. The name of this genre came from the tradition that when many men gathered in a barbershop they would sing with no musical instruments.
Contemporary is the most popular kind of a cappella these days. For this kind, the "bass" line should be stronger, and the "chorus" (all the singers except for bass, percussion, and solo) should have variety. The percussion should make their sound more like drums. This genre is similar to 'doo-wop' but the "chorus" part is more complex and has a variety of sound effects.
Doo-wop is also getting more popular because of its simple style. Even though it has simple moto (Italian for "progression of music"), it can be interesting with great vocal and chorus.
- Holmes, William C. A cappella. Grove Music Online. Oxford Music Online. http://www.oxfordmusiconline.com/subscriber/article/grove/music/00091. Retrieved 21 September 2008.