a method for determining how well configurations for a gas turbine propulsion system attain selected acoustic wave energy emissions criteria based on acquiring a plurality of acoustic frequency spectra representations of a noise representation therefor over an operating duration . relative peaks in the acoustic frequency spectra representations are then located and the forms of at least one of those peaks is altered with respect to acoustic frequency in manners substantially matching acoustic wave energy emissions changes corresponding to configuration changes in gas turbine propulsion systems which are then evaluated to provide an operating parameter noise value . one of those operating parameter noise values that best meets the selected acoustic wave energy emissions criteria is used to aid in determining corresponding configurations changes to thereby better meet those criteria . this foregoing method can be incorporated into a process for determining an overall configuration for a gas turbine propulsion system .