Word-intelligibility tests at various intensity levels were administered to a crew of trained listeners in the presence of recorded noise from jet and propeller-driven aircraft. The noise was that which would be present outdoors and in a house as the result of engine runup operations and if aircraft were flying overhead shortly after takeoff and prior to landing. According to visual inspection of the data, methods of measuring or evaluating aircraft noise predict the results of the speech tests in the following order of merit, from best to worst: (1) articulation index (AI), (2) perceived noise level in PNdB, (3) speech-interference level (SIL), (4) noise criteria (NC), (5) over-all sound-pressure level (SPL A scale), and (6) over-all SPL C scale. The differences among PNdB, SIL, NC, and dB (A), in this regard, are probably not significant according to these tests.