New aircraft concepts with distributed propulsion systems are currently developed for urban and regional air mobility. Typically, these propulsion systems consist of a large amount of propulsors, such as ducted fans or propellers. As the emitted sound fields of individual propulsors may interact with each other, the noise emission is characterized by interference effects. These interactions change the psychoacoustic characteristics of distributed propulsion systems compared to conventional designs with two or four engines. Therefore, in this paper acoustic interactions due to rotational speed fluctuations are investigated for a distributed propulsion system equipped with 26 ducted, low-speed fans. Synthesized flyover sounds are generated using an analytical auralization process for different ranges of rotational speed fluctuations and the impact on noise immission as well as psychoacoustic sound quality metrics is assessed. Our study indicates that temporal fluctuations decrease with increased rotational speed fluctuations. Time signals are smoothed when speed fluctuations are applied, resulting in lower values for psychoacoustic loudness, tonality and fluctuation strength.

Correction Notice In the Acknowledgements section the project VIRLWINT should also be listed. The following statement should be included: This publication is part of the project VIRLWINT (Virtual acoustical twin of distributed propulsion systems) funded by the German Aerospace Center (DLR). The affiliation for author S. Schade should be changed to: German Aerospace Center, Bismarckstraße 101, 10625 Berlin, Germany The affiliation for author P. Ratei should be changed to: German Aerospace Center, Hein-Saß-Weg 22, 21229 Hamburg, Germany The affiliation for author S. Bartels should be changed to: German Aerospace Center, Linder Höhe, 51147 Köln, Germany The affiliation for author R. Jaron und A. Moreau should be changed to: German Aerospace Center, Bismarckstraße 101, 10625 Berlin, Germany.