The current techniques available for predicting interior noise levels are outlined, and the limitations of these techniques, particularly in their application to future high‐speed aircraft, are discussed. The relative importance of each external noise source is discussed, with special emphasis on the boundary layer, the engines, and the wake. Interaction of the noise sources and the effect of this interaction on interior noise predictions are mentioned—for example, the interaction of the engine noise on the boundary layer pressure field. Also, the anticipated exterior noise levels for future aircraft are estimated. Presented curves, obtained from flight test data, laboratory measurements, and analysis, compare transmission loss through the fuselage side wall (skin plus soundproofing) of a modern transport airplane. In the commentary on these results, an attempt is made to explain the discrepancies between the predictions. The relative merit of each prediction method is discussed, together with that of another method, namely, a boundary layer test facility. In conclusion, the paper contains a brief discussion explaining the influence that aircraft interior noise requirements have on the design of fuselage side walls, including skin gage, damping properties, and stringer and frame spacings.