I have been looking for environmental coupling to the aLIGO electronics located by the SUS and SEI test stands in the Y arm of the LVEA. To test for vibrational coupling, I used speakers and shakers (photograph below shows accelerometer and shaker on one of the cabinets). I shook each rack using a 5 Hz ramped sawtooth, and looked for evidence of the 5 Hz comb in many of the working channels by looking for coherence between the channel and the accelerometer channel. Even though I shook the racks with more than 100 times the amplitude of the ambient background at most frequencies (see plot) I found no evidence of coupling - good job CDS.