Advanced Noise Indicator Mapping Relying on a City Microphone Network.

In this work, a methodology is presented for city-wide road traffic noise indicator mapping. The need for direct access to traffic data is bypassed by relying on street categorization and a city microphone network. The starting point for the deterministic modeling is a previously developed but simplified dynamic traffic model, the latter necessary to predict statistical and dynamic noise indicators and to estimate the number of noise events.

Protective effect of restorative possibilities on cognitive function and mental health in children and adolescents: A scoping review including the role of physical activity.

Background The exposome approach can be a powerful tool for understanding the intertwining of social, physical, and internal influences that shape mental health and cognitive development throughout childhood. To distil conceptual models for subsequent analyses, the EU-funded project Early Environmental quality and Life-course mental health effects (Equal-Life) has conducted literature reviews on potential mediators linking the exposome to these outcomes. We report on a scoping review and a conceptual model of the role of restorative possibilities and physical activity.

Equations for finite-difference, time-domain simulation of sound propagation in moving media with arbitrary Mach numbers.

Finite-difference time-domain (FDTD) techniques for sound propagation have become increasingly popular. In moving media, such as the atmosphere, starting equations for FDTD calculations are often limited to low Mach numbers, which may result in significant errors. In this article, two coupled equations for the sound pressure and acoustic particle velocity are derived from the linearized fluid dynamic equations.

Associations between Personal Attitudes towards COVID-19 and Public Space Soundscape Assessment: An Example from Antwerp, Belgium.

The COVID-19 pandemic, and the lockdown events and policies that followed, led to significant changes in the built environment and how it is experienced by people and communities. Among those, variations in the acoustic environments were some of the most noticeable in cities. This study investigated the relationships between the perception of the acoustic environment (i.

Computational modeling of a single-element transcranial focused ultrasound transducer for subthalamic nucleus stimulation.

Objective: While transcranial focused ultrasound is a very promising neuromodulation technique for its non-invasiveness and high spatial resolution, its application to the human deep brain regions such as the subthalamic nucleus (STN) is relatively new. The objective of this study is to design a simple ultrasound transducer and study the transcranial wave propagation through a highly realistic human head model. The effects of skull morphology and skull and brain tissue properties on the focusing performance and energy deposition must therefore be known.

Variability due to short-distance favorable sound propagation and its consequences for immission assessment.

The specific noise immission from an (industrial) noise source is commonly assessed by short-term measurements. Good practice prescribes measuring under downwind conditions at modest wind speeds. Nevertheless, this still leads to large variation, even at short distances and needs quantification.

Personal Audiovisual Aptitude Influences the Interaction Between Landscape and Soundscape Appraisal.

It has been established that there is an interaction between audition and vision in the appraisal of our living environment, and that this appraisal is influenced by personal factors. Here, we test the hypothesis that audiovisual aptitude influences appraisal of our sonic and visual environment. To measure audiovisual aptitude, an auditory deviant detection experiment was conducted in an ecologically valid and complex context.

Influence of Personal Factors on Sound Perception and Overall Experience in Urban Green Areas. A Case Study of a Cycling Path Highly Exposed to Road Traffic Noise.

In contemporary urban design, green public areas play a vital role. They have great societal value, but if exposed to undue environmental noise their restorative potential might be compromised. On the other hand, research has shown that the presence of greenery can moderate noise annoyance in areas with high sound levels, while personal factors are expected to play an important role too.

Sound propagation from a ridge wind turbine across a valley.

Sound propagation outdoors can be strongly affected by ground topography. The existence of hills and valleys between a source and receiver can lead to the shielding or focusing of sound waves. Such effects can result in significant variations in received sound levels.

An airborne acoustic method to reconstruct a dynamically rough flow surface.

Currently, there is no airborne in situ method to reconstruct with high fidelity the instantaneous elevation of a dynamically rough surface of a turbulent flow. This work proposes a holographic method that reconstructs the elevation of a one-dimensional rough water surface from airborne acoustic pressure data. This method can be implemented practically using an array of microphones deployed over a dynamically rough surface or using a single microphone which is traversed above the surface at a speed that is much higher than the phase velocity of the roughness pattern.

Simplified analytical model for sound level prediction at shielded urban locations involving multiple diffraction and reflections.

Accurate and efficient prediction of the sound field in shadow zones behind obstacles is a challenging task but essential to produce urban noise maps. A simplified method is presented to predict sound levels at shielded urban locations, including multi-edge diffraction over successive buildings and multiple reflections between parallel façades. The model is essentially based on Pierce's diffraction theory, where the Fresnel Integral is approximated by trigonometric functions for efficient evaluation, and parameterized for urban environments.

Airborne sound propagation over sea during offshore wind farm piling.

Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km.

Multi-criteria anomaly detection in urban noise sensor networks.

The growing concern of citizens about the quality of their living environment and the emergence of low-cost microphones and data acquisition systems triggered the deployment of numerous noise monitoring networks spread over large geographical areas. Due to the local character of noise pollution in an urban environment, a dense measurement network is needed in order to accurately assess the spatial and temporal variations. The use of consumer grade microphones in this context appears to be very cost-efficient compared to the use of measurement microphones.

Sound absorption of porous substrates covered by foliage: experimental results and numerical predictions.

The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound).

A computational model of auditory attention for use in soundscape research.

Urban soundscape design involves creating outdoor spaces that are pleasing to the ear. One way to achieve this goal is to add or accentuate sounds that are considered to be desired by most users of the space, such that the desired sounds mask undesired sounds, or at least distract attention away from undesired sounds. In view of removing the need for a listening panel to assess the effectiveness of such soundscape measures, the interest for new models and techniques is growing.

Quantifying scattered sound energy from a single tree by means of reverberation time.

Trees in urban spaces surrounded by buildings may be effective in dispersing sound energy, and this could affect sound level distribution and street canyon reverberation. To quantify this effect of trees with a view to including it in numerical predictions, this paper examines sound scattering from a single tree in open field by means of reverberation time (RT). Five trees of different species and crown sizes were considered.

Reverberation-based urban street sound level prediction.

Street reverberation can strongly increase sound pressure levels in urban streets. In noise mapping models on the other hand, including a sufficient number of reflections is computationally very costly. A simple regression model is developed in this study, based on typical street width and façade height or façade roughness in old city centers of many European cities.

Annoyance, detection and recognition of wind turbine noise.

Annoyance, recognition and detection of noise from a single wind turbine were studied by means of a two-stage listening experiment with 50 participants with normal hearing abilities. In-situ recordings made at close distance from a 1.8-MW wind turbine operating at 22 rpm were mixed with road traffic noise, and processed to simulate indoor sound pressure levels at LAeq 40 dBA.

Focused study on the quiet side effect in dwellings highly exposed to road traffic noise.

This study provides additional evidence for the positive effect of the presence of a quiet façade at a dwelling and aims at unraveling potential mechanisms. Locations with dominant road traffic noise and high L(den)-levels at the most exposed façade were selected. Dwellings both with and without a quiet façade were deliberately sought out.

Evolution of building façade road traffic noise levels in Flanders.

The evolution of daytime façade noise levels by road traffic at 250 dwellings in Flanders is assessed. Three identical man-operated measurement campaigns have been conducted in the years 1996, 2001 and 2009, during fall. A practical methodology has been developed, based on short time noise measurements and context observations at these locations.

Noise measurements as proxies for traffic parameters in monitoring networks.

The present research describes how microphones could be used as proxies for traffic parameter measurements for the estimation of airborne pollutant emissions. We consider two distinct measurement campaigns of 7 and 12 days, at two different locations along the urban ring road in Antwerp, Belgium, where sound pressure levels and traffic parameters were measured simultaneously. Noise indicators are calculated and used to construct models to estimate traffic parameters.

Sampling approaches to predict urban street noise levels using fixed and temporary microphones.

Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (prediction of 15 min and 60 min evolution of L(Aeq) and statistical levels L(A90,)L(A50) and L(A10)) noise level monitoring are investigated in this paper. Noise levels are measured for 72 consecutive days at 5 neighboring streets in an inner-city noise measurement network in Gent, Flanders, Belgium. We present a method to make predictions based on a fixed monitoring station, combined with short-term sampling at temporary stations.

On the ability of consumer electronics microphones for environmental noise monitoring.

The massive production of microphones for consumer electronics, and the shift from dedicated processing hardware to PC-based systems, opens the way to build affordable, extensive noise measurement networks. Applications include e.g.

Correlation analysis of noise and ultrafine particle counts in a street canyon.

Ultrafine particles (UFP, diameter<100 nm) are very likely to negatively affect human health, as underlined by some epidemiological studies. Unfortunately, further investigation and monitoring are hindered by the high cost involved in measuring these UFP. Therefore we investigated the possibility to correlate UFP counts with data coming from low-cost sensors, most notably noise sensors.

Meteorological influence on sound propagation between adjacent city canyons: a real-life experiment.

Sound propagation between a courtyard and an adjacent street canyon, as influenced by a wide range of meteorological conditions, was investigated by means of a real-life experiment in a dense urban setting. During several months, test signals were emitted on a regular base by an outdoor loudspeaker in the courtyard and recorded by wall-mounted microphones in the courtyard and the street canyon. Detailed meteorological observations were made at nearby buildings with sensors at roof level.