Most Rock songs are written in the key of A or E. The next most common
key is C. This is because the electric guitar can be easily tuned in
these keys and the electric guitar is the lead instrument in Rock bands.
However, the guitar depends on the distinctive Rock beat. Rock would
not be Rock with out the drums. It’s the beat that gets the blood
pumping; it’s the heartbeat of the electric guitar. That Rock beat has
been cited as evidence that Rock is the Devil’s Music. This seems
strange though, because the very quality of the Rock beat that is
disturbing to some, had its beginning in early African religious
drumming, it nourished a sense of spiritual passion.
With this fact in mind, its not hard to understand why those teenage girls in the late 40s and all through the 50s, when Rock became mainstream, cried, screamed, and fell in love with Rock stars. It’s a passionate beat. The one that caused the fright was the backbeat. In the 4/4 time signatures, there was a new twist, at least new to mainstream America. Instead of the emphasis being on the first beat and the third beat, as in standard music, it was on the second beat and the fourth beat. If you say 1, 2, 3, 4, aloud, changing the emphasis with your voice you can feel the difference. Some Rock is written in 5/4 time, another 7/8 time. However, these are considered odd signatures.
African American music has been, and still is, a key influence on Rock,
especially the innovative rhythms and uses of all types of percussion
instruments. There are characteristic riffs, recurring patterns,
backbeats, accent on the 2nd and 4th beats in 4/4 time,
call-and-response patterns, and syncopation, stresses on beats that
would normally not be stressed. However, Syncopation is not exclusive
to Rock, it is incorporated in virtually all popular music. It is the
deliberate disturbance of the 2 or 3-beat stress pattern and usually
lays stress on a weak accent. It disturbs the expected triggering, one
surprise after another.
Rock drummers are not tied to form. Drumbeats are always being invented and altered by creative drummers. Most of these innovations find a home in Rock music. Bo Diddley, American singer-songwriter, 1928 -2008, popularized a beat, forever after called the Bo Diddley Beat, that served to make rhythm the prominent feature instead of the chord progressions, frequently there were no chord changes in the entire song. As a young man he played on Chicago street corners and so it follows that the Bo Diddley Beat, which today is a regular part of Rock percussion, was inspired by street performers who played the beat by slapping their arms, legs, chest, and cheeks while chanting the lyrics. The rhythm was the song.