Masking question - link to file included

Hi

I am attempting to create an animation using a noise field via the cell pattern effect.

The animation will consist of geometrical shapes which will be masks for various colour patterns.

how can I use the random cell pattern to make the edge of the shape oscillate slightly?
i.e. the shape consists of lots of 'random dots' but has a hard edge, how can I isolate the edge so that it is 'fuzzed' as part of the effect
and the edge itself appears to approximate a circle rather than have a hard edge.
to do this I imagine the edge of the circle needs to be isolated.

many thanks in advance

here is a link to the file (AFX cc 2014 file)

https://www.dropbox.com/sh/d7paomdmyktc21y/AADPBGrJaylwq9AbYsjHEnIRa?dl=0

Very helpful thank you

can you offer any advice using expressions to add further randomness to the movement of the circles.

I believe that the cell pattern effect is a random distributionon a frame by frame basis, wheras the circles in cc ball appear to move on a path or a walk.

many thanks

Paul