Interdisciplinary Auralization of Take-off and Landing Procedures for Subjective Assessment in Virtual Reality Environments

Abstract

The issue of aircraft noise experienced by residents in the airport's neighborhoods is one of subjective annoyance and a presentation of noise intensity in decibels alone might not be sufficient to give a clear understanding of noise abatement measures being carried out or the effect for instance of constructing a new runway at an airport. Although noise contours can be a great way of a quick assessment of noise impact over larger areas, noise quantified in numbers can prove lacking in capturing the actual annoyance caused by the noise to the residents. For this reason, a method providing a more subjective assessment of aircraft noise impact is required and auralization of complete aircraft movements could be one such way of better capturing the annoyance due to noise caused by aircraft. The Virtual Air Traffic System Simulation (VATSS) interdisciplinary project of RWTH Aachen University has the aim of presenting the effect of complete aircraft movements via visualization and auralization of aircraft noise in 3-D Virtual Reality environments for the subjective assessment of aircraft noise. This paper focusses on the interdisciplinary collaboration of the Institute of Aerospace Systems and the Institute of Technical Acoustics of RWTHAachen to produce a capability of auralizing complete time-dependent take-off and landing procedures up to an altitude of 3000 meters. The noise produced by a conventional aircraft with a turbofan engine is modeled and the ILR's capability to model aircraft noise for complete 4-D take-off and landing procedures is shown along with the technique to auralize complete standard procedures as well as noise abatement procedures with time-varying settings. Both broadband and tonal noise components for dominant sources are auralized for the movements. Nomenclature t e = emission time t reception = reception time t delay = time delay c = speed of sound h = aircraft altitude s source-obs = straight path distance between aircraft and observer f = frequency/harmonic frequency 2 B = number of fan rotor blades M = Mach number θ = polar directivity angle φ = phase v i = i th voxel (cuboid volume element) s = distance D = atmospheric attenuation

Interactive simulation of aircraft noise in aural and visual virtual environments

“…Section 3.1 also describes the efforts at the ILR of attempting to capture aircraft noise annoyance via metrics that describe the quality of the sound and not just the level. The overall VR simulation technique was developed for an interdisciplinary internal RWTH Aachen University project, VATSS -Virtual Air Traffic System Simulation, which had the goal of making aircraft noise more communicable to non-experts by making the use of Virtual Reality technologies [16]. The motivation behind the interdisciplinary approach was the view that such a complex VR simulation of air-traffic encompassed more than one specialized field and thus could be performed in the most efficient way by utilizing the already existing expertise at the specialized institutes (see Fig.…”

Virtual air traffic system simulation — Aiding the communication of air traffic effects

“…Auralization The aircraft noise is auralized entirely in realtime [6]. Only flight-path-and atmosphere-dependent data, like directivities, are precomputed.…”

Ground Reflection with Turbulence Induced Coherence Loss in Flyover Auralization

“…A phase offset occurs when the two waves reach the microphone position since the travel time of the ground reflected ray is always larger than the direct ray. This effect is explicitly apparent when calculating the root-mean-square (rms) version, (5) where Q = |Q|e ij with a phase change j due to the ground reflection and the ground attenuation |Q|. In case of auralizations including an acoustically soft ground, Q is transformed into an FIR filter and applied to the ground reflected path.…”

“…Besides aircraft or route related differences, auralizations may aid in explaining day to day differences due to weather [3]. Other applications range from various aircraft types [4] or re-synthesis of measured flyover noise [5].…”