The noise generated by ventilated supercavities has been explored experimentally in a water tunnel facility. The most prominent acoustical characteristic is the monopole behavior exhibited by a ventilated supercavity in its pulsating closure regime. The interior cavity pressure and near-field radiated sound are monotonic with a frequency that is related to the speed and length of waves propagating on the supercavity gas/water interface. The cavity interior pressure spectrum level is shown to be related to the near-field and far-field noise spectrum level through spherical spreading of the sound waves from the supercavity interface. As a result, the cavity interior pressure can be used as a measure of the radiated noise. The noise radiated by a pulsating supercavity at the pulsation frequency is at least 40 dB above that radiated by comparable re-entrant jet and twin vortex cavities.