Purpose of Review

This review aims to evaluate and discuss the current advances in the measurement and assessment of the noise generated by unconventional aircraft, such as unmanned aircraft systems (UAS) and urban air mobility (UAM) vehicles. Building upon the findings of this review, research gaps are identified, and further work is proposed to enhance existing and emerging methods for the appropriate noise management of these advanced air mobility (AAM) technologies.

Recent Findings

Noise has been highlighted as one of the key concerns for the wider deployment of UAS and UAM operations. This is suggested to be due to having acoustic signatures with sound characteristics commonly associated with noise annoyance, such as ‘sharpness’ (the perceived proportion of high-pitched sonic energy) and ‘tonality’ (the perceptual prominence of concentrated sonic energy at discrete frequencies). These types of ‘psychoacoustic features’ are thought to be connected with observations of increased noise annoyance for AAM, compared with conventional aircraft and road vehicles, at the same level of sound exposure.

Summary

In the last few years, there has been a growing body of research on UAS and UAM noise. Research has focused on a comprehensive understanding of the sound sources of these unconventional aircraft under a wide range of operating and operational conditions. Based on gathered evidence, measurement protocols for both laboratory and field studies are very advanced for the acoustic characterisation of UAS in terms of sound level, frequency and directivity. Looking at the human response to UAS and UAM noise, loudness has been consistently reported as the main contributor to noise annoyance, with second-order contributions from other psychoacoustic features, such as sharpness, tonality and ‘amplitude modulation’ (fluctuations in loudness over time), varying among studies. Noise targets for UAS certification have been derived from existing regulations for conventional aircraft and rotorcraft, but might not account for the usually reported annoyance offset between UAS/UAM and conventional vehicles. Key research gaps identified include the lack of studies focusing on multiple events, and deeper understanding of the influence that personal or contextual factors may have on responses, which will be important for the development of robust methods for the assessment and minimisation of community noise annoyance due to the operation of these unconventional aircraft.

Graphical Abstract

中文翻译：

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非常规飞机的噪声：当前测量技术、心理声学、指标和法规的回顾

审查目的

本综述旨在评估和讨论非常规飞机（例如无人机系统（UAS）和城市空中机动（UAM）车辆）产生的噪声的测量和评估的当前进展。根据本次审查的结果，确定了研究差距，并提出了进一步的工作，以加强对这些先进空中机动（AAM）技术进行适当噪声管理的现有和新兴方法。

最近的发现

噪音已成为更广泛部署 UAS 和 UAM 操作的关键问题之一。这被认为是由于具有通常与噪声烦恼相关的声音特征的声学特征，例如“锐度”（高音调声音能量的感知比例）和“音调”（离散频率下集中声音能量的感知突出度） ）。这些类型的“心理声学特征”被认为与在相同的声音暴露水平下，与传统飞机和道路车辆相比，AAM 噪音增加的观察结果有关。

概括

过去几年，关于 UAS 和 UAM 噪声的研究不断增多。研究重点是全面了解这些非常规飞机在各种运行和操作条件下的声源。根据收集到的证据，实验室和现场研究的测量协议对于无人机的声级、频率和方向性声学特性来说非常先进。观察人类对 UAS 和 UAM 噪声的反应，响度一直被认为是噪声烦恼的主要贡献者，其他心理声学特征的二阶贡献，例如锐度、音调和“幅度调制”（响度随时间的波动） ），不同研究有所不同。UAS 认证的噪声目标源自传统飞机和旋翼机的现有法规，但可能无法解释通常报告的 UAS/UAM 与传统车辆之间的干扰抵消。已确定的主要研究差距包括缺乏针对多个事件的研究，以及缺乏对个人或背景因素可能对反应产生的影响的更深入了解，这对于开发用于评估和最小化社区噪音烦恼的稳健方法非常重要这些非常规飞机的操作。

图形概要