This is basic tut (I rushed the idea so if there are any questions etc please ask)
You have a model and set up a percent pose slider that controls model you can have more than 1 pose and sound and or frequency but this is basic
so we have model with pose in chor have an action with just the sound on the model then we go into the models pose as pictured below right click and pick amplitude
This will show window were you select same sound and set low and high percent of pose you can then hit visualize and see how the sound frequency effect the loudness(amplitude) of the sound and select accordingly (hit escape key to end visualization)
this will add info to pose settings
Then you can play chor and see results
amplitudesample.mov
Here are sound and project file
amplitudetut.zip