If you sing a song, and you want to show the importance of a note, or squeeeeeeeze the emotion out of it, how do you do it? How about if you play the violin? The drums? Chances are, the first thing that comes to mind is to use volume, or dynamics, to do so. Swell a note, make others quieter, perform sudden dynamic shifts - ah, that's what music is all about!
But wait a second - what if you want to do that on the bagpipes?
You probably have already realized this is true; you can't change volume (or even insert silences) when you play your pipes. There is NO dynamic range. Ouch!
The reason for this is that all of our reeds are connected to the bag, and the bag provides a continuual (hopefully perfectly continual) airflow. So, you get one pressure, and that's it! So, major bummer? Or....
An opportunity to express in other ways! Bagpipers rely heavily on the idea of expression, which could be roughly translated to mean bending the usual rules of rhythm, in order to simulate dynamics. We can't make notes physically louder or softer, but, if we add length to a note, it will seem louder. The same is true if we take time away from a note; it'll seem softer.
A lot of what we teach at Dojo U deals with this idea specifically. In particular, we talk about dynamics that occur inside of beats with our "ALAP/ASAP" concept. As far as dynamics that happens outside of beats (or phrasing, perhaps?), we use the idea of pulsing quite a bit. Check it out some time!