Loudspeaker engineers are laughing their asses off at this! This is several orders of magnitude worse than the worst speakers ever made. "coherence" is magic-speak for "heavily averaged total system distortion / non-linearity + noise" which include the transducer measurement device and physical environment. To put it simply, the vibration source, test fixture and measurement transducer have to be calibrated before measuring the DUT. Duh! Since the system and DUT can be quite massive, and each DUT requires different mounting fixtures, this needs to be performed before making measurements of the DUT. Two major issues with this sort of test (i.e. "gotchas") are finding the location to mount the transducers(s) on the DUT and since the test system has automatic gain and massive time averaging, it does not show the instantaneous behavior and stresses on the DUT (because they are compensated and averaged out).
For reference, back in the 60's, US guided missiles had small fins to steer them. These operated at up to 10, kHz. and were under high mechanical stress during flight of the missile. Very high speed cameras filming the fins were used to see the deformations and resonances.