I guess, you want volume bars as in equalizers? Each bar in equalizer is a part of spectrum. You must calculate this this data.
I don't know After Effects good enough, so I don't know way to calculate part spectral part of sound. Maybe some plugins? If I can had such task, I can write some tiny app which will analyze sound and print data.
Plugin or external application must write data as keyframes in positions/scales of bars. You can copy-paste key frames and generate your own in text format.
When you have keyframes, just copy it to bar layout (or make this object as parent of bar-layer). Like you can do with tracking markers.
As workaround: you can draw traditional spectrum on picture, then place some motion trackers on it and track bars positions. Then you can transfer data to your custom-made bars. This is not perfect and some time consume, but it will works.