Future Low-Noise Aircraft Technologies and Procedures - Perception-based Evaluation Using Auralised Flyovers

Abstract

Residents living in the vicinity of airports are exposed to noise from departing and approaching aircraft. Noise may be reduced by introducing novel aircraft technologies and flight procedures. By means of auralisation and listening experiments, such possible future changes can be evaluated by considering human sound perception. In this study, flyovers of different aircraft types and flight procedures were auralised at multiple virtual observer locations, and subsequently evaluated in a psychoacoustic laboratory experiment with respect to short-term noise annoyance. Approaches of an existing reference aircraft, a possible low-noise retrofitted version and a future low-noise design were simulated with standard and tailored procedures. Separate source signals were synthesised for engine broadband, fan tone, airframe broadband, and cavity tone noise. Further, smooth transitions between configurations and operational conditions were modelled to create realistic sounds. To increase plausibility, the propagation simulation considered ground reflection and frequency-dependent amplitude modulation due to propagation through a turbulent atmosphere. The flyover sounds were spatially reproduced by a hemispherical loudspeaker array. The listening experiment revealed significant annoyance reductions for low-noise aircraft types and flight procedures, that maximal benefit is achieved by the combined optimization of aircraft technology and procedure, and that distributed observers need to be considered.