ESDU 05001 provides a means of estimating the noise levels in one-third octave bands resulting from the combustion process within a gas turbine engine which may be either static or flying. The prediction program accompanying this Item is based on the semi-empirical SAE method. The main input parameters that need to be specified are the mass flow rate through the engine core@ the combustor inlet total pressure@ the total temperature rise across the combustor and the total temperature fall across the turbine system at the maximum take-off condition. An additional program to facilitate the generation of input files is included.