  The effects of Macroscopic Quantum Tunneling (MQT) and Coulomb Blockade (CB)
in Josephson junctions are of considerable significance both for the
manifestations of quantum mechanics on the macroscopic scale and potential
technological applications. These two complementary effects are shown to be
clearly distinguishable from the associated noise spectra. The current noise is
determined exactly and a rather sharp crossover between flux noise in the MQT
and charge noise in the CB regions is found as the applied voltage is changed.
Related results hold for the voltage noise in current-biased junctions.
