Bob Marley: "No Woman No Cry"
Here's part of the intro. The guitar plays downbeats in measure 1, right on the ruler ticks. The circled detail shows where a downbeat has been anticipated-- played a eighth note early:
The accented off-beat sets up rhythmic tension, which needs to be resolved later.
Four measures later (directly below, in the rectangle), the same trick is used, with a subtle difference. Again the downbeat sound is played ahead of the true downbeat location. Unlike before, it's played exactly an eighth note ahead: on a weak beat, but right on it. The circled note, upon inspection, is actually ahead of the ruler tick. It's subtle in the image, but definitely audible.
The circled note is an example of a grace note-- a slight but noticeable anticipation. The anticipated downbeat in measure 6 manages to resolve lingering tension from measure 2, yet still leave lower-level tension that continues into the first verse.
This song is a great example of how pop songs chart out. It has a highly regular structure and consistent tempo throughout. Variation occurs mostly in the decoration of the lead part.
Looking down any of these columns-- the 2nd measure of each verse, for instance-- you can see that each verse uses the same template.
Reggae has the genre property that the bass drum plays on upbeats and the (treble) guitar plays downbeats (usually it's the other way around), which is pretty clear in the image. Interestingly, though, it's not true in the four introductory measures.
© 2003-9 N. Resnikoff