The results of semiempirical analytical and experimental studies of the acoustic frequency response of circular tubes with a mean turbulent flow are given. For the frequency range tested, it is seen that the hypothesis of a time-invariant eddy viscosity profile across the tube predicts the behavior well. For lower frequencies a simple lag in the turbulence profile from its equilibrium values is hypothesized which should be of moderate importance in acoustic behavior and of great importance in large-amplitude behavior. The lag is estimated using the steady-flow results of Goldberg.