A short sound pulse, transmitted horizontally between two points in deep ocean water, arrives at the receiver as a continuous superposition of time‐separated wavepackets. This fact has been demonstrated by a detailed analysis of the crosscovariance between such pulses carrying a phase reversal and atruncatedreplica. In all, about 280 pulses were selected from over 3000 that were previously studied [N. W. Lord, J. Acoust. Soc. Am.36, 1043(A) (1964)] for the transmission time fluctuation. For these 1200‐cps pulses, the phase spreading becomes tangible at a range of 7 km, where it is approximately π/3, or about 0.2 msec. As an estimate ofinstantaneous phase spread, this value is reasonable as compared to the transmission‐time fluctuation, for this range, of 0.7 msec between pulses spaced every 0.6 sec. The use of a truncated replica on a long pulse depresses most of the side‐lobe crosscovariance peaks. The magnitude of the central peak is related to both the phase spreading and the chosen length of the truncated replica, although this latter dependence is lost by a slow phase reversal. Hence, for these measurements, if Δ is the phase spread, the magnitude of the crosscovariance peak is (sinΔ)/Δ. At ranges under 7 km, Δ is small and the peak is close to unity with small fluctuation. At ranges over 7 km, the peak declines and fluctuates more among the successive pulses. [Hudson Laboratories of Columbia University Informal Documentation No. 108. Work supported by the U. S. Office of Naval Research.]