Rhyme Scheme

There is tremendous complexity in the rhythms of rap.  Not so in rhyme schemes.  Two are popular:
1. A A, B B, C C, D D, etc.
2. A, A, A, A, A, A, A etc… B, B, B, B, B, C, C, C, C, C, etc….

There is only one song that follows A B A B C D C D etc. that I know of: The Magic Number, by De La Soul:

Difficult preaching is Posdnous’ pleasure
Pleasure and preaching starts from the heart
Something that stimulates the music in the measure
Measure in the music breaks in three parts

If proof were needed

Proof that rap is implicitly governed by prosodic rules is that rap sounds very different from other spoken word music genres such as reggaeton and dancehall.  They share with rap the basic system of stresses in 4/4 time but are very different in other respects.  Comparing the two will be a good way to understand the rules that govern each.

Of course, there are not rules in the sense that they cannot be broken.  ‘Convention’ is the better word.  What are all the conventions, and how do they vary with space and time?  In other words, what separates Atlanta rap prosodically from New York rap, and New York rap of 2008 from 1992, 1992 from 1982?

The basic unit is the bar

The basic unit of rap is the bar. The time signature is always 4/4. In its most basic form, each bar contains four stresses that are delivered at regular intervals:

.    x                x                x            x
.  back in the day when I was a teenager

.      x              x                  x                 x
. before I had status and before I had a pager

The xs mark the position of the stresses. A note: ‘teenager’ is accented differently than in normal speech but does not sound strange in the song; this is typical. (Actually the word ‘teenager’ itself is accented the same way in the song “Gold and a Pager” by The Cool Kids.)