When a series of uniform acoustic pulses is transmitted through a medium whose refractive index varies in a random manner, the received pulses vary randomly about an average amplitude. A theory developed by Mintzer [J. Acoust. Soc. Am.25, 922 (1953)] predicts that the coefficient of variationV, defined as the fractional standard deviation of a series of pulses, is directly proportional tok(2&pgr;/acoustic wavelength), provided that the range from the source to receiver is greater thanka2, whereais the correlation distance of the refractive index variations. In a scaled model experiment the refractive index variations are caused by heating the medium (water) from below, thus causing turbulent convection. Observations show the linear dependence ofVupon frequency forr>ka2as predicted by the theory. At the higher frequencies, observations indicate possible oscillations inVas it tends toward a frequency independent value.