Measurements were made of the energy per unit‐area spectrum level of the shock wave 100 yd from 1‐lb TNT charges exploded underwater. Over the frequency range covered, 0.1–25 kc/sec, the measurements were in agreement with values calculated, using peak pressures and time constants reported by Arons. In particular, the decrease in spectrum level with increasing frequency of 6 dB per octave at high frequencies, characteristic of pulses with short rise times, continued up to the high‐frequency limit of the measuring equipment.