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Measurements were made of the random variation produced in the amplitudes of sonic pulses propagated through a water medium in which was induced a nearly homogeneous random perturbation in temperature. The measurements were carried out at frequencies of 480 kHz and 1.42 MHz for transmitter-to receiver separations ranging from 1638 to 7658 in. The amplitude variations of the received pulses were analyzed to determine their time autocorrelation and variance as functions of range, i.e., transmitter-to-receiver separation and frequency. It was found that the time autocorrelation of the sonic-pulse amplitudes was equivalent to that measured for the temperature microstructure. The variance in sonic-pulse amplitude was determined as a function of range at both operating frequencies. These findings are compared with the theoretical findings of Mintzer and Bergmann. An equivalence of the time autocorrelation of sonic-pulse amplitude and temperature microstructure predicted by theoretical considerations is indeed supported by, experimental findings; however, the observed dependence of variance on range fell between the linear dependency predicted by Mintzer and the third-power dependency predicted by Bergmann. This was expected, since the frequency distance and parameters were in between the extremes assumed in those derivations.

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