Quantification of the Psychoacoustic Effect of Noise from Small Unmanned Aerial Vehicles

This paper presents the results of a study evaluating the human perception of the noise produced by four different small quadcopter unmanned aerial vehicles (UAVs). This study utilised measurements and recordings of the noise produced by the quadcopter UAVs in hover and in constant-speed flight at a fixed altitude. Measurements made using a ½″ microphone were used to calculate a range of different noise metrics for each noise event. Noise recordings were also made using a spherical microphone array (an Eigenmike system). The recordings were reproduced using a 3D sound reproduction system installed in a large anechoic chamber located at The University of Auckland. Thirty-seven participants were subjected to the recordings and asked to rate their levels of annoyance in response to the noise, and asked to perform a simple cognitive task in order to assess the level of distraction caused by the noise. This study discusses the noise levels measured during the test and how the various noise metrics relate to the annoyance ratings. It was found that annoyance strongly correlates with the sound pressure level and loudness metrics, and that there is a very strong correlation between the annoyance caused by a UAV in hover and in flyby at the same height. While some significant differences between the distraction caused by the UAV noise for different cases were observed in the cognitive distraction test, the results were inconclusive. This was likely due to a ceiling effect observed in the participants’ test scores.

Community noise from urban air mobility (UAM) and its control by traffic management

The awareness about UAM is amplified by steadily growing numbers of air taxi concepts being announced. In general environmentally friendly by electric propulsion, community noise and en-route noise are still prominent open questions. Several studies for larger UAM aircraft, describing the acoustic characteristics of a variety of potential air taxi concepts, have been performed by the author. Due to the abovementioned multitude of different vehicle concepts and their multiple operational conditions, each of them shows individual sound characteristics. Therefore, further investigations of noise created by air taxi fleets appear to be crucial. Understanding of community noise around vertiports and along air taxi routes will strongly depend on those fleets. In this paper, acoustically different air taxi systems are composing different sets of air taxi fleets, used for air traffic noise simulations. The simulations start with baseline scenarios of equally represented taxi systems on fixed flight paths with several flight levels in a certain air lane. The final fleets are consisting of random air taxi composition with randomly populated flight paths. The results, based on common noise metrics and changes in the number of affected residents, could provide a first indication how to reduce community noise by future UAM traffic management.

Community noise from a drone delivery distribution center: challenges and options

As drone package delivery services are expanded, community noise will be an issue that every operator will need to consider. Drones represent a unique new community noise source that will operate and be perceived differently than traditional aircraft and ground transportation vehicles. It is also likely that some early implementations of drone delivery services by major retailers will operate out of existing distribution centers, which may not be ideally located from a noise perspective. This study considers potential drone delivery noise in the community surrounding an existing distribution center, assuming the facility were to be utilized as the hub of a future drone package delivery service. The predicted noise levels from drone deliveries are compared to typical community noise limits, and potential alternative noise metrics for assessing annoyance from drone noise in communities are discussed. Options to reduce community noise from drone deliveries by altering flight altitude and speed, utilizing different flight path routing strategies, and taking advantage of the potential masking of drones by existing roadway noise are considered.

Optimization of Takeoff Departure Procedures for Airport Noise Mitigation

The environmental effects of aviation, particularly community noise exposure, is one of the major barriers to a sustainable growth in passenger air traffic. With an increasing number of aircraft operations and growing urban population, several major airports around the world have implemented various noise mitigation strategies. One such mitigation strategy is to optimize the departure procedures utilized by aircraft for performing takeoff operations. Present-day noise abatement departure procedures are developed by airlines under the guidance of the International Civil Aviation Organization and regulatory entities such as the Federal Aviation Administration. These procedures are generally limited to two per aircraft type and are therefore developed for averaged flight conditions. A generic methodology has been developed here which accounts for external parameters, such as the elevation and weather conditions at the departure airport, and aims to design optimal departure procedures per set of external conditions. By retaining these variables in the procedure design process, their influence on various metrics of interest can be studied. A case study is performed using three different airports each at a standard day and a hot day weather condition. Noise metrics are evaluated at four locations relative to the runway. Fuel consumption is also calculated to account for airline operating costs. The results show that the optimality of a procedure is sensitive on both external factors, as well as metrics being evaluated. While some noise metrics require a tradeoff with fuel consumption over a set of pareto optimal solutions, at certain locations, the two are optimized simultaneously by a single procedure.

Signal to Noise Considerations in Single Pixel Multiphoton Microscopy

Single-pixel imaging geometries for wide-field multiphoton microscopy (SPx-MPM) have emerged as a contender to conventional point-scanning multiphoton systems (PS-MPM) for deep tissue imaging. These systems are thought to be faster due to their multiplexed imaging capabilities with higher photon throughput. In this study we numerically compare the signal to noise metrics of the SPx-MPM to the PS-MPM systems. Our results suggest that PS-MPM systems outperform SPx-MPM systems, despite their higher photon throughput.

NRN1 and CAT Gene Polymorphisms, Complex Noise, and Lifestyles Interactively Affect the Risk of Noise-Induced Hearing Loss

Background: Multiple genetic and environmental factors influence the severity of NIHL. However, few studies have reported interactions among such factors in modulating the risk of NIHL. This study aimed to assess for interactions among gene polymorphisms, noise metrics, and lifestyles on the risk of NIHL.Methods: A case-control study was conducted using 307 patients with NIHL and 307 matched healthy individuals from five manufacturing industries. General demographic data, lifestyle details, and noise exposure levels were recorded. The kompetitive allele-specific polymerase chain reaction (KASP) was used to analyze the genotypes of 18 single nucleotide polymorphisms (SNPs). The generalized multifactor dimensionality reduction (GMDR) method was used to examine the effects of all possible interactions. Results: The proportion of people with complex noise exposure, high CNE, high adj-CNE, smoking, propensity to watch loud videos, or sedentary lifestyle was significantly greater in the NIHL group than in the healthy group (P < 0.05). The GMDR model demonstrated a relevant interaction between NRN1 rs3805789 and CAT rs7943316. Subjects with the SNP pair of NRN1 rs3805789-CC and CAT rs7943316-AT, NRN1 rs3805789-CT and CAT rs7943316-AA, NRN1 rs3805789-CT and CAT rs7943316-TT, NRN1 rs3805789-CT/TT and CAT rs7943316-AA, or NRN1 rs3805789-CC and CAT rs7943316-AT/TT had higher risks of NIHL than those with NRN1 rs3805789-CC and CAT rs7943316-AA (P < 0.05). There was an interaction among NRN1 rs3805789, CAT rs7943316, and kurtosis. Subjects exposed to complex noise and carrying both NRN1 rs3805789-CT and CAT rs7943316-TT or NRN1 rs3805789-CT/TT and CAT rs7943316-AA had higher risks of NIHL than those exposed to steady noise and carrying both NRN1 rs3805789-CC and CAT rs7943316-AA (P < 0.05). The best six‐locus model involving NRN1 rs3805789, CAT rs7943316, smoking, video volume, physical exercise, and working pressure for the risk of NIHL was found to be the interaction (P = 0.0010). An interaction was also found among smoking, video volume, physical exercise, working pressure, and kurtosis (P = 0.0107).Conclusions: Complex noise, high CNE, high adj-CNE, smoking, high video volume, and sedentary lifestyle are environmental risk factors for NIHL. Concurrence of NRN1 rs3805789 and CAT rs7943316 constitutes a genetic risk factor for NIHL. Complex noise exposure significantly increases the risk of NIHL in subjects with a high genetic risk score. Interactions between genes and lifestyle as well as noise metrics and lifestyle affect the risk of NIHL. These results provide a theoretical basis for screening genetic and environmental risk factors to prevent NIHL.

Noise metrics analysis in schools near airports: A Brazilian case study

This study compares metrics for environmental noise diagnosis in schools at airport vicinity. The goal is to analyze and identify the most suitable criteria for scaling aircraft noise impact over schools, during landing and take-off operations. A Brazilian case study is conducted, based on the noise mapping and sound level verification. The day-night average noise level (DNL) and the time above limit (TA) are investigated using acoustic simulation and noise mapping and in order to identify the critical receivers. Results of DNL and TA for two schools at airport surroundings show that the criteria adopted by the municipal and airport authorities to describe the airport noise are unsatisfactory and do not reflect the intermittent behavior of this type of noise. It was verified that individual receiver analysis, based on noise interruptions thought TA parameter is more suitable for evaluation of noise impact over schools at airport vicinity.