Drone Noise Emission Characteristics and Noise Effects on Humans—A Systematic Review

Abstract

The number of operations of Unmanned Aerial Vehicles (UAV), commonly referred to as “drones”, has strongly increased in the past and is likely to further grow in the future. Therefore, drones are becoming a growing new source of environmental noise pollution, and annoyance reactions to drone noise are likely to occur in an increasing share of the population. To date, research on drone noise emission characteristics, and in particular also on health impacts, seems scarce, but systematic overviews on these topics are missing. The objective of this study was to establish a systematic literature review on drone noise emissions and noise effects on humans. The paper presents the methodology of the systematic reviews performed separately for noise emission and noise effects, assembles current literature, gives an overview on the state of knowledge, and identifies research gaps. Current literature suggests that drone noise is substantially more annoying than road traffic or aircraft noise due to special acoustic characteristics such as pure tones and high-frequency broadband noise. A range of open questions remains to be tackled by future studies.

Investigation of Metrics for Assessing Human Response to Drone Noise

“…SQMs provide an accurate representation of huma hearing perception [ 15 , 33 ]. The most widely used SQMs are loudness (measured in sone), sharpness (measured in acum), fluctuation strength (measured in vacil), roughness (measured in asper), tonality (measured in tonality units—TU), and impulsiveness (measured in impulsiveness units—IU).…”

“…Hui et al [ 3 ] outlined the main sound generation mechanisms in drones, highlighting the contributions of rotor noise and electric motors. Schäffer et al [ 15 ] conducted a systematic review (based on the PRISMA statement) on current methods for acoustic measurements and noise emission characteristics of drones; they also stated the requirements for a drone emission model and proposed a scheme for data acquisition. Overall, the sound emission of drones was found to be mainly influenced by drone size, configuration (number of rotors), payload, operating conditions and flight manoeuvres.…”

“…Schäffer et al [ 15 ] carried out a systematic review on the effects of drone noise on humans, finding that the literature on the topic is still very limited. Christian and Cabell’s work [ 16 ] was pioneering in understanding the perception of drone noise and how it compared to other sources of transportation, such as road traffic.…”

“…Current evidence suggests that drone noise annoyance highly depends on loudness-related metrics [ 3 , 15 , 16 ]. However, Hui et al [ 3 ] suggested that further research is needed to understand and quantify the effect of spectral and temporal factors (including tonality and impulsiveness) on drone noise annoyance.…”

“…However, Hui et al [ 3 ] suggested that further research is needed to understand and quantify the effect of spectral and temporal factors (including tonality and impulsiveness) on drone noise annoyance. Schäffer et al [ 15 ] also point out pure tones and high-frequency broadband noise as important contributors to drone noise annoyance. Tonal and high-frequency drone noise is also likely to increase its noticeability in existing soundscapes [ 19 , 20 , 21 ] and therefore lead to noise annoyance.…”