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The assessment of aircraft noise for community noise impact and certification has till now been performed conventionally using the A-weighted decibel (dBA) and Effective Perceived Noise Level (EPNL) metrics respectively. Although these metrics have sufficed till now for conventional noise assessment, the renewed interest in unconventional engines such as Counter Rotating Open-Rotor (CROR) engines and the much stronger tonal content their spectra contain may require new unconventional metrics, which fully capture the individual characteristics and complexities of aircraft noise. The focus of this paper shall be on the annoyance aspect of aircraft noise rather than solely on intensity and how this annoyance could be incorporated and minimized during conceptual aircraft design. The research builds on the previous research into aircraft noise annoyance at RWTH Aachen where the sound quality metrics of loudness and tonality were compared to the more conventional metrics dBA, PNL, PNLT and EPNL for standard and noise abatement aircraft procedures 1 . The same approach shall now be applied to aircraft and engine design parameters. It will be seen what influence various design parameters such as number of fan blades and stator vanes, fan tip design Mach number, primary and secondary jet areas, wing span and wing area among others, have on the annoyance caused by aircraft noise via the sound quality metrics of loudness, tonality and sharpness. This will be done using the ILR Noise Simulation and Assessment module -INSTANT. A comparison will be made for the currently used conventional metrics, to see if the sound quality metrics capture more information than dBA and EPNdB both for community as well as certification noise assessment. Also, an attempt shall be made for minimal aircraft noise annoyance optimization during conceptual design, via a reduced tonality variant of selected aircraft, using the conceptual aircraft design and optimization environment MICADO 2 of the ILR. The research in this paper is intended as a follow-up to the work carried out for the interdisciplinary internal RWTH Aachen project -Virtual Air Traffic System Simulation (VATSS) 3,4 which had the aim of making aircraft noise more easily communicable via auralization and 3D visualization of air-traffic. NomenclaturedBA = A-Weighted decibel PNL = Perceived Noise Level PNLT = Tone-corrected Perceived Noise Level EPNL = Effective Perceived Noise Level SPL = Sound Pressure Level, relative to 0.00002 Pa W/S = Aircraft wing-loading MTOW = Maximum Take-Off Weight SLST = Sea-Level Static Thrust B = Number of fan rotor blades V = Number of fan stator vanes RS = Fan rotor-stator spacing Mt,d = Fan blade tip design Mach number Afan = Fan inlet area 2 Ajet_1 = Primary jet area Ajet_2 = Secondary jet area BPR = Engine Bypass Ratio S = Wing area ΛLE = Wing leading edge sweep angle b = Wing span N1 = Fan rotation speed (Engine Low-Pressure spool speed) M = Flight Mach number V = Flight airspeed h = Flight altitude N = Loudness N′ = Specific Loudness z = Critical ban...

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