Experimental assessment of sound quality metrics for takeoff and landing aircraft

The reduction of aircraft noise over the past decades has generated a growing awareness that the characteristics of a signal can be equally or more important to annoyance than the sound pressure level. Sound can be perceived as more annoying, depending on the frequency content or tonal components. The sound quality metrics loudness, roughness, sharpness, and tonality are important tools to characterize sound. Flyover measurements of landing and takeoff aircraft are investigated in terms of sound quality metrics. The experimental dataset includes 141 measurements of 14 landing aircraft types and 160 measurements of 12 takeoff aircraft types. The sound quality metrics are compared for different aircraft types, and their variability within the same aircraft is investigated. Possible correlations of the sound quality metrics with the airframe, engines, and aircraft operational conditions are investigated. This analysis provides empirical expressions that show a good agreement with experimental data for loudness, sharpness, and roughness for takeoff aircraft. For landing aircraft, empirical expressions could only be obtained for loudness and tonality.