The rap structure is almost always in 4/4 time signature. It uses swing
emphasis found in many jazz songs for the base of it's beat. There is most commonly 6 16th notes per beat. The instrumentation
of rap is drawn from disco, funk, and older R n' B. Rap beats are so different because Dj's sample from many different songs,
and take pieces of the beat to combine with other pieces to create a master beat. Drums/bass is in almost every rap song.
A rap group consists of one or more rappers and a DJ (Disc Jockey). The rappers are the ones rhyming and doing vocals, while
the DJ spun the beat for the rappers to rhyme over. Originally, DJ's would create "Backing Tracks" (Under the Rappers' vocals)
by playing 2 records and changing back and forth to create a cutting and mixing technique. After a while, scratching (rotating
a vinyl disc back and forth by hand to create cool sounds) was created. The scratching technique was soon the most popular
of all techniques. In the early 80's, computer generated sound from synthesizers and programmable drum machines were invented.
These took the place of the DJ in a rap group, and rappers could make more money. All other DJ techniques were obsolete once
computers came into play. Nowadays, rappers use a better version of the computer synthesizers to record tracks.