The measurement of transmission loss in the ocean using explosive sources requires knowledge of the spectrum level of the energy released in a given frequency band as it would be measured as in a boundary‐free medium. For the case of shallow charges the measurement of these spectrum levels is often complicated by the fact that the refracted and surface‐reflected arrivals, each containing an initial impulse followed by a series of bubble pulses, cannot be separated by the usual technique of receiver gating. In recent measurements of the spectrum level of 1.8‐lb charges detonated at 60 ft, this difficulty has been obviated by separation of the two arrivals in the frequency domain rather than in the time domain. This was done by smoothing the spectrum of the recorded waveform to reduce the wide variation caused by oscillations of the gas bubble and then adjusting the smoothed spectrum by the amounts necessary to account for the Lloyd's Mirror interaction. The results obtained in this way agree well with values for deeper explosions reported by Christian [E. A. Christian, J. Acoust. Soc. Amer.42, 905–907 (1967)] at the upper end of the spectrum where the levels are nearly depth independent. [Work supported by the U. S. Navy Electronic Systems Command.]