I think I am starting to see more how this is going to work now.
On the arduino module, I set it to "tell" the rmp3 to getspectrumanalyser(), which will then return a frequency value to my arduino module, and if it is above a certain frequency will trigger and output to a motor.
Can this be used to trigger an action for groups of different ranges of frequencies, a low frequencies group, medium and high? Rather than just if the frequency goes above a set value?