Streets classification models by urban features for road traffic noise estimation.

Road traffic is the primary source of environmental noise pollution in cities. This problem is also spreading due to inadequate urban expansion planning. Hence, integrating road traffic noise analysis into urban planning is necessary for reducing city noise in an effective, adaptable, and sustainable way. This study aims to develop a methodology that applies to any city for the stratification of urban roads by their functionality through only their urban features. It is intended to be a tool to cluster similar streets and, consequently, traffic noise to enable urban and transportation planners to support the reduction of people's noise exposure. Three multivariate ordered logistic regression statistical models (Model 1, 2, and 3) are presented that significantly stratify urban roads into five, four, and three categories, respectively. The developed models exhibit a McFadden pseudo-R2 between 0.5 and 0.6 (equivalent to R2 >0.8). The choice between Model 1 or 2 depends on the scale of the city. Model 1 is recommended for developed cities with an extensive road network, while Model 2 is most suitable in intermediate and growing cities. On the other hand, Model 3 could be applied at any city scale but focused on local management of transit routes and for designing acoustic sensor installations, urban soundwalks, and identification of quiet areas. Urban features related to road width and length, presence of transport infrastructure, and public transport routes are associated with increased traffic noise in all three models. These models prove useful for future action plans aimed at reducing noise through strategic urban planning.

Dataset for polyphonic sound event detection tasks in urban soundscapes: The synthetic polyphonic ambient sound source (SPASS) dataset.

This paper presents the Synthetic Polyphonic Ambient Sound Source (SPASS) dataset, a publicly available synthetic polyphonic audio dataset. SPASS was designed to train deep neural networks effectively for polyphonic sound event detection (PSED) in urban soundscapes. SPASS contains synthetic recordings from five virtual environments: park, square, street, market, and waterfront. The data collection process consisted of the curation of different monophonic sound sources following a hierarchical class taxonomy, the configuration of the virtual environments with the RAVEN software library, the generation of all stimuli, and the processing of this data to create synthetic recordings of polyphonic sound events with their associated metadata. The dataset contains 5000 audio clips per environment, i.e., 25,000 stimuli of 10 s each, virtually recorded at a sampling rate of 44.1 kHz. This effort is part of the project ``Integrated System for the Analysis of Environmental Sound Sources: FuSA System'' in the city of Valdivia, Chile, which aims to develop a system for detecting and classifying environmental sound sources through deep Artificial Neural Network (ANN) models.

Development and application of practical criteria for the recognition of potential Health Restoration Soundscapes (HeReS) in urban greenspaces.

Urban greenspace soundscapes can contribute to the restorative effects that nature provides for the psychological and emotional health of people when certain conditions are met. The main objective of this paper is to propose practical criteria to help planners and managers in the design, development and preservation of urban greenspaces whose soundscapes may contribute to the renewal of health. Systematic literature review informed a conceptual potential Health Restoration Soundscapes (HeReS) model, based on five conditions: (1) Naturalness, (2) Sound Levels, (3) Perceived Sound Sources, (4) Soundscape Assessment, and (5) Sensescape Coherence and proposed Health Restoration Soundscapes Criteria (HeReS-C), for HeReS evaluation in urban green areas. The HeReS-C were applied in 21 sites in Argentina, Sweden, and Chile. General results are provided for all 21 sites, along with three in-depth profiles of HeReS-C applications that provide case studies across a range of resulting HeReS-C scenarios, including sites that meet the HeReS-C criteria, those that do not, and sites that could qualify in the future, if appropriate management measures are taken. HeReS-C showed to be a promising tool for the recognition of potential health-restoring soundscapes in urban greenspaces; informing their design and management to favor the well-being and health of the population.

Analytical modeling of dissipative silencers.

This paper applies ideas originally developed in the field of acoustics of multiscale porous media to the analytical modeling of dissipative silencers. Analytical models for the long-wavelength acoustical properties of different types of dissipative silencers, such as pod silencers, lined ducts, splitters, and bar silencers, are introduced in this work. Some of these models account for the possibility of using different porous materials in a given silencer. For instance, a model for a splitter silencer comprising baffles made of different porous materials is derived. Examples of the sound transmission behavior of the said types of silencers are presented to evidence that the dissipation of sound energy is largely influenced by pressure diffusion occurring in the porous constituents. The predictions of the analytical models are in good agreement with finite element calculations.

A Green Soundscape Index (GSI): The potential of assessing the perceived balance between natural sound and traffic noise.

Urban soundscapes are dynamic and complex multivariable environmental systems. Soundscapes can be organized into three main entities containing the multiple variables: Experienced Environment (EE), Acoustic Environment (AE), and Extra-Acoustic Environment (XE). This work applies a multidimensional and synchronic data-collecting methodology at eight urban environments in the city of Córdoba, Argentina. The EE was assessed by means of surveys, the AE by acoustic measurements and audio recordings, and the XE by photos, video, and complementary sources. In total, 39 measurement locations were considered, where data corresponding to 61 AE and 203 EE were collected. Multivariate analysis and GIS techniques were used for data processing. The types of sound sources perceived, and their extents make up part of the collected variables that belong to the EE, i.e. traffic, people, natural sounds, and others. Sources explaining most of the variance were traffic noise and natural sounds. Thus, a Green Soundscape Index (GSI) is defined here as the ratio of the perceived extents of natural sounds to traffic noise. Collected data were divided into three ranges according to GSI value: 1) perceptual predominance of traffic noise, 2) balanced perception, and 3) perceptual predominance of natural sounds. For each group, three additional variables from the EE and three from the AE were applied, which reported significant differences, especially between ranges 1 and 2 with 3. These results confirm the key role of perceiving natural sounds in a town environment and also support the proposal of a GSI as a valuable indicator to classify urban soundscapes. In addition, the collected GSI-related data significantly helps to assess the overall soundscape. It is noted that this proposed simple perceptual index not only allows one to assess and classify urban soundscapes but also contributes greatly toward a technique for separating environmental sound sources.

A comprehensive methodology for the multidimensional and synchronic data collecting in soundscape.

The soundscape paradigm is comprised of complex living systems where individuals interact moment-by-moment among one another and with the physical environment. The real environments provide promising conditions to reveal deep soundscape behavior, including the multiple components involved and their interrelations as a whole. However, measuring and analyzing the numerous simultaneous variables of soundscape represents a challenge that is not completely understood. This work proposes and applies a comprehensive methodology for multidimensional and synchronic data collection in soundscape. The soundscape variables were organized into three main entities: experienced environment, acoustic environment, and extra-acoustic environment, containing, in turn, subgroups of variables called components. The variables contained in these components were acquired through synchronic field techniques that include surveys, acoustic measurements, audio recordings, photography, and video. The proposed methodology was tested, optimized, and applied in diverse open environments, including squares, parks, fountains, university campuses, streets, and pedestrian areas. The systematization of this comprehensive methodology provides a framework for soundscape research, a support for urban and environment management, and a preliminary procedure for standardization in soundscape data collecting.

Assessment of methods for simplified traffic noise mapping of small cities: Casework of the city of Valdivia, Chile.

In many countries such as Chile, there is scarce official information for generating accurate noise maps. Therefore, specific simplification methods are becoming a real need for the acoustic community in developing countries. Thus, the main purpose of this work was to evaluate and apply simplified methods to generate a cost-effective traffic noise map of a small city of Chile. The experimental design involved the simplification of the cartographic information on buildings by clustering the households within a block, and the classification of the vehicular traffic flows into categories to generate an inexpensive noise map. The streets have been classified according to the official road classification of the country. Segregation of vehicles from light, heavy and motorbikes is made to account for traffic flow. In addition, a number of road traffic noise models were compared with noise measurements and consequently the road traffic model RLS-90 was chosen to generate the noise map of the city using the Computer Aided Noise Abatement (CadnaA) software. It was observed a direct dependence between noise levels and traffic flow versus each category of street used. The methodology developed in this study appears to be convenient in developing countries to obtain accurate approximations to develop inexpensive traffic noise maps.

Comparison of occupational noise legislation in the Americas: an overview and analysis.

The workplace contributes significantly to the total dose of daily noise to which a person is subjected. Therefore, millions of people around the world are exposed to potentially dangerous noise levels and consequently, there is an urgent, global need for legislation to adequately protect the auditory health of workers. Occupational noise legislation has been adopted in many of the countries with different degrees of comprehensiveness and varying levels of sophistication. This paper presents a global view of current legislation on occupational noise in the 22 countries that make up the Americas, that is, Latin America, Canada, and the United States. Upon analysis of the legislation, there are notable differences among countries in the defined values for permissible exposure limit (PEL) and exchange rate. Of the countries that have regulations, the majority (81%) use a PEL of 85 dBA. A PEL of 85 dBA and the 3-dB exchange rate are currently used by 32% of the nations in the Americas. Most nations limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB (or dBC), while a few use slightly lower limits. However, 27% of the countries in the region still have not established regulations with respect to permissible noise levels and exchange rates. This fact is leaving millions of workers in the Americas unprotected against occupational noise. Provide an overview and analysis of the current legislation on occupational noise in the 22 countries that make up the Americas. The information on legislation, regulations, and standards discussed in this paper were obtained directly from official government sources in each country, the International Labour Organization database, or through various colleagues in each country. (1) There are notable differences among countries in the defined values for PEL and exchange rate. (2) Of the countries that have regulations, the majority (81%) use a PEL of 85 dBA. A PEL of 85 dBA and the 3-dB exchange rate are currently used by 32% of the nations in the Americas. (3) Most nations limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB (or dBC), while a few use slightly lower limits. (4) 27% of the countries in the region still have not established regulations with respect to permissible noise levels and exchange rates. (5) Millions of workers in the Americas are unprotected against occupational noise.

On the sound radiation from a circular hatchway.

Low-frequency sound radiation from vibrating plates is a practical problem often found in engineering applications. In this article, the sound radiation from a circular hatchway is examined using a discrete approach based in the acoustic resistance matrix. Since this matrix can be combined with the volume velocity vector on the discretized vibrating circular surface, the sound radiation efficiency can be estimated through matrix approaches. The limitation of the approach is discussed by using benchmark results presented in previous works. The method produces acceptable results in low frequencies when the response of the plate is dominated by one low structural mode. When the response of more than one mode is significant, the method gives good estimation of the total sound power just for frequencies up to the first resonance. However, the method can be applied to complex and irregular vibrating plane surfaces.

Potential problems with environmental sound barriers when used in mitigating surface transportation noise.

The public, increasingly well-informed about the problem of excessive noise, is taking actions for the development of new transport infrastructure projects and improvement of existing infrastructure. In addition, many countries have implemented mandatory Environmental Impact Assessment procedures. As a result, the construction of sound barriers has become a common measure, which can be used by an agency to mitigate potentially significant noise impacts. A sound barrier, eventually, will become part of the surrounding landscape and could be a cause of impact for ecosystems, the road users and those who live alongside the road. Basically, this article discusses these potential effects in the context of environmental assessment procedures. In addition, results of a pilot survey conducted at a residential area affected by the construction of a barrier are presented. Although most residents felt that sleeping conditions improved after the barrier was built, most important negative reactions are the loss of sunlight and visual impact.