Main aspects of environmental protection from urban noise

The main sources of noise pollution in modern cities, that generate significant levels of sound pressure, which significantly, sometimes at times exceed permissible noise levels have been identified. The consequences of the negative impact of noise of the urban environment on the human body, fauna and flora are described. The sanitary-hygienic, engineering-technical, architectural-planning, construction-acoustic and economic-social aspects of scientific researches concerning protection of the environment from noise pollution are singled out. The main methods and ways to reduce urban noise are described, among which are: reducing the sound power level of existing equipment and vehicles, or replacing them with less noisy ones, and during design-taking measures to minimize noise emissions from machines; carrying out timely cleaning, adjustment, repair of machines, mechanisms and equipment, restriction or complete prohibition of noisy works and operation of the most intensive noise sources at night; rational orientation of the noise source or place of noise radiation, taking into account the direction indicator; placement of noise sources and objects of protection – at the maximum possible distance from each other; the use of building structures with improved sound insulation, the use of sound-absorbing materials for lining the enclosing structures of buildings and structures; zoning of sources and objects of protection, application of territorial gaps, noise protection buildings, acoustic screens and strips of greenery. It was found that the maximum possible impact on noise pollution of modern cities and surrounding areas can be achieved in the case of integrated application of methods, means of protection against acoustic blocking of the duration, direction and use of noise emissions in its sources and through noise level on the way to its spread, as well as through the implementation of appropriate organizational and technical measures.

Urban noise distributions and the influence of geometric spreading on skewness

Statistical distributions of urban noise levels are influenced by many complex phenomena, including spatial and temporal variations in the source level, multisource mixtures, propagation losses, and random fading from multipath reflections. This article provides a broad perspective on the varying impacts of these phenomena. Distributions incorporating random fading and averaging (e.g., gamma and noncentral Erlang) tend to be negatively skewed on logarithmic (decibel) axes but can be positively skewed if the fading process is strongly modulated by source power variations (e.g., compound gamma). In contrast, distributions incorporating randomly positioned sources and explicit geometric spreading [e.g., exponentially modified Gaussian (EMG)] tend to be positively skewed with exponential tails on logarithmic axes. To evaluate the suitability of the various distributions, one-third octave band sound-level data were measured at 37 locations in the North End of Boston, MA. Based on the Kullback-Leibler divergence as calculated across all of the locations and frequencies, the EMG provides the most consistently good agreement with the data, which were generally positively skewed. The compound gamma also fits the data well and even outperforms the EMG for the small minority of cases exhibiting negative skew. The lognormal provides a suitable fit in cases in which particular non-traffic noise sources dominate.

Urban Noise Exposure and Cardiometabolic Diseases: An Exploratory Cross-Sectional Study in Lisbon

<b><i>Introduction:</i></b> Urban noise pollution has been associated with an increased risk of developing metabolic syndrome. Nevertheless, existing observational studies relating to noise exposure and metabolic syndrome are based on non-generalizable cohorts. Lisbon remains a noisy city where this association has not been evaluated, and for this reason, we studied the relationship between exposure to urban noise and the prevalence of type 2 diabetes mellitus, obesity, and hypertension. <b><i>Methods:</i></b> Diurnal, evening and nocturnal noise emission levels were obtained for each street in the city from the Lisbon noise map. After allocation of all roads to the respective parish of Lisbon, the noise emission for each parish was averaged for each day period. The number of adult patients with type 2 diabetes mellitus, obesity and hypertension in 2014, 2015 and 2016 in each parish of Lisbon was obtained from the Regional Health Administration of Lisbon and Tagus Valley. Prevalence as a percentage of the population was determined using the number of residents in each parish determined in the 2011 population census. Spearman’s non-parametric correlation coefficient was used due to the non-normal distribution of the variables, at the 5% significance level (α = 0.05). <b><i>Results:</i></b> No correlations were found between daytime, afternoon or night-time noise exposure and the prevalence of type 2 diabetes mellitus, obesity or hypertension, although correlations were found between the cardiometabolic variables. Nevertheless, noise levels in Lisbon were above the legally established limit and the World Health Organization guidelines for environmental noise exposure in the European region. <b><i>Conclusion:</i></b> Our results do not agree with previous studies and should be faced as preliminary due to a strong biological plausibility for an association between noise exposure and cardiometabolic diseases and to encourage further studies, with longitudinal cohorts.

Acoustic Behavior and Design of Large Urban Spaces – Canyon and Tunnel

Residents of large urban centers are daily exposed to urban noise pollution, especially to noise generated by traffic of vehicles. Environmental noise may harm the environment and the population's quality of life. Therefore, studies that aim to reduce the effects of noise pollution are extremely relevant. In urban divisions, there must be spaces between or in buildings to ensure access for people and vehicles. However, regarding sound transmission, these spaces are considered "weak points" as they ease the passage of urban noise to other spaces that have housing. Thus, this study, carried out in the city of Stuttgart/Germany, evaluates the influence of urban spaces called tunnel and canyon on the transmission of traffic noise to residential facades posterior to these spaces. Two locations were selected: the first with the presence of a tunnel-like space and the second with a canyon-like space. Through measurements and acoustic simulations, the current sound environment of the places was measured. In acoustic simulations, variations of geometric aspects and sound absorption coefficients of the internal surfaces of open spaces were also considered. The results show that the dimensions of open spaces are significant in sound transmission, especially the parameters width and height. The data also show that the installation of coatings with sound absorption on the internal surfaces of spaces is a viable measure from a technical point of view, as it resulted in an attenuation of up to 22 dB(A) on posterior facades.

Influence of microclimatic elements on sound propagation in Amazonian cities: The case of urban noise in Belem.

Many studies have shown that microclimatic elements influence the sound propagation in cities, and can contribute to increasing or decreasing the urban noise. This paper aims to discuss the relationship between main microclimatic elements - air temperature, air humidity, atmospheric pressure and winds - and the noise caused by road traffic in an Amazonian urban environment, in order to emphasize the importance of urban planning instruments be adapted to the specific microclimatic conditions, promoting the improvement of the urban environment from more efficient building strategies for controlling the sound pollution. For this, it's used as basis a theoretical framework on the topic, meteorological data from Brazil's National Institute of Meteorology and illustrative maps of the city of Belem. It was found that the temperature, humidity and atmospheric pressure, for this microclimate, do not collaborate for reducing road traffic noise, leaving this responsibility to the winds (air ventilation) and the way they behave within the built urban mass. KEYS Urban noise - Urban Microclimate - Amazonian environment

Effects of urban noise variability on cognitive abilities in indoor spaces: Gender differences

Previous evidence has shown that exposure to urban noise negatively influences some cognitive abilities (i.e. verbal fluency and delayed recall of prose memory) of people in indoor spaces. However, long-standing literature in the cognitive domain has reported that men and women can show different performance on cognitive tasks. Here, we aimed to investigate if and how different patterns of perceived urban noises in indoor environments could affect male and female participants’ cognitive abilities. Ambisonic sound recordings representing scenarios with varying noise patterns (low, medium and high variability) were acquired with an open window at three dwellings in a southern Italian city. As a control condition, the recordings were caught inside a quiet room. While exposed to theses four auditory conditions, participants had to perform cognitive tasks assessing free verbal memory recall, auditory–verbal recognition and working memory. The results show that male and female participants have a different tolerance to noise patterns. Women overperform men on verbal tasks, while the contrary effect emerges with men outperforming women on visuospatial working memory tasks.