A previous study of intense broad-band noise in a tube [F.M. Pestorius and D.T. Blackstock, “Finite-Amplitude Wave Effects in Fluids,” in Proceedings 1973 Symposium, Copenhagen (IPC Science and Technology, Guildford, England, 1974), pp. 24–29] showed that propagation distortion is significant for plane waves at sound pressure levels encountered in jet noise fields. We have modified our computer program to account for spherical spreading. Using measured noise near actual jets as the input for our program, we have computed the distortion that is expected to occur during subsequent propagation. Computations have been made for noise from a model supersonic jet (data furnished by Lockheed-Georgia Co. in the form of 1/3-octave-band spectra) and from a T38 aircraft (tape-recorded noise provided by NASA Langley). In both cases, the computed waveforms exhibit shocks and other evidence of nonlinear effects at moderate distances. However, our model does not include atmospheric attenuation, ground effects, and distributed source effects. These effects may severely limit the importance of nonlinear propagation distortion. Thus much work remains to be done. [Research supported by DOT and AFOSR.]