Do recent findings on jet noise answer aspects of the Schultz curve?

Abstract

Recent research efforts on nonlinear propagation from high performance jet aircraft have revealed an interesting challenge to predicting community response. This challenge focuses on receiver perception of these unique acoustical signals, which contain acoustical shocks that appear to increase their relative loudness and/or noisiness. This current finding suggests a need for an improved description of a receiver perception of the loudness of these signals in order to improve the assessment of noise impacts from these aircraft. Looking backwards, an interesting question emerges: did the earlier low bypass jet engines on commercial and transport aircraft also include these acoustical shocks? If they did contain these features, then the perceptual differences observed between aircraft and other transportation noise sources may be partially explained. FIGURE 3. Nonlinearity analysis of a recording of a Boeing 757. (Upper) Histograms of the normalized time derivative of the pressure waveform, with a zoomed-in version on the right. (Lower) The Morfey-Howell / nonlinearity indicator. ACKNOWLEDGMENTSThe authors gratefully acknowledge David Dubbink for allowing access to the high-quality aircraft recordings.