Rosendo Vílchez-Gómez

A categorization method applied to the study of urban road traffic noise

The present work summarizes a study of the hypothesis that urban noise can be stratified by measuring street noise according to a prior classification of a towns streets according to their use in communicating the different zones of the town. The method was applied to five medium-sized Spanish towns (Vitoria-Gasteiz, Salamanca, Badajoz, Cáceres, and Mérida) with populations ranging from 218 000 down to 50000 and with different socio-economic characteristics, climate, etc. As the initial hypothesis of the work was that traffic is the main source of urban noise and is also the principal cause of the variability of the sound levels measured in urban settings, the study focused only on the five nonpedestrian categories of streets. The continuous equivalent sound level (Leq) was employed in the statistical analysis as it is commonly used as a general noise index, and other noise indicators such as L(DN) or L(DEN) are calculated from it. It was found that, although differences between the medians were not statistically significant in some of the towns for certain pairs of adjacent categories, the differences between pairs of nonadjacent categories were always significant, indicative of the stratification of noise in these five towns. Further studies on other medium-sized towns and on large towns and small villages would be needed to test whether the present definition of street categories is extensible elsewhere without modification.

Possible relation of noise levels in streets to the population of the municipalities in which they are located

A preview of the results of applying a categorization method to twenty towns with populations between 2200 and 700 000 inhabitants and areas between 0.57 km(2) and 59 km(2) is presented. This represents a significant expansion of the population size and area of urban sites studied by this method, with variations of two to three orders of magnitude, including the fourth most populous town in Spain. It is found that there is a relationship between urban noise and inhabitants, and also between urban noise and inhabited area, reflecting the urban structure defined in the strata of the categorization method.

Effects of Leisure Activity Related Noise in Residential Zones

An analysis of two noise surveys of the city of Cáceres is presented. The first was made for 400 inhabitants living throughout the city, and the second for 50 inhabitants of a conflictive zone due to noise during the night, mainly at weekends. The similarity of the two groups of persons interviewed was studied and verified. Then a comparison was made of the responses referring to disturbing noise sources and effects of noise. The results showed appreciable differences between the two surveys. Some continuous sound pressure level measurements made over several days are also presented. They show major differences in the sound levels between the zone and the rest of the city.

Can weekly noise levels of urban road traffic, as predominant noise source, estimate annual ones?

The effects of noise pollution on human quality of life and health were recognised by the World Health Organisation a long time ago. There is a crucial dilemma for the study of urban noise when one is looking for proven methodologies that can allow, on the one hand, an increase in the quality of predictions, and on the other hand, saving resources in the spatial and temporal sampling. The temporal structure of urban noise is studied in this work from a different point of view. This methodology, based on Fourier analysis, is applied to several measurements of urban noise, mainly from road traffic and one-week long, carried out in two cities located on different continents and with different sociological life styles (Cáceres, Spain and Talca, Chile). Its capacity to predict annual noise levels from weekly measurements is studied. The relation between this methodology and the categorisation method is also analysed.

Sound Quality in Urban Environments and its Relationship With Acoustic Parameters

Different urban environments were analyzed acoustically, using 32 recordings obtained with binaural techniques of recording and reproduction. The relationships of the perception of pleasantness/unpleasantness as described by a sample of 25 inhabitants of these urban environments with two psychoacoustic parameters (loudness and sharpness) and the traditional measure of equivalent sound level (dBA) were analyzed in two forms, one using a verbal scale, and the other a numerical value for that perception. Highly significant correlations were found between the perception of an environment as very unpleasant and the parameters considered for its acoustic characterization. The mean of the numerical value used to express the sensation of liking was significantly correlated with the three sound parameters.

Noise Pollution and Urban Planning

Noise pollution distribution in each city around the world is necessarily influenced by its own design. A lot of factor associated to urban planning have a considerable effect on volume of traffic, vehicles distribution, traffic conditions, etc. And it is know that, from a temporal and spatial point of view, the most important source of noise in cities is road traffic. For that, good relationships between urban planning and different factors such as urban density, urban morphology, urban land use, street distribution, street environment and green spaces are being founded. In this way, the fact of finding a sustainable city could be closer, at least with respect to noise pollution. A good knowledge of these relationships would allow better prediction, analysis and prevention of such pollution through an effective design of urban environments. However, although in the first decade of XXI century these relationships were treated in some works, only some aspects of these problems were considered, essentially focused on street functionality. In the last years, this topic has reached more important development and more studies focused on the analysis of the relationships between the distributions of pollution and urbanism. This work makes a revision of spatial sampling methodologies for noise pollution assessment in relation with urban planning and a review of studies that have analysed the relationships between urban noise and different specifics aspects of urban design.

Analysis of an early measurement of the speed of sound propagation in the atmosphere

Abstract Spanish and French scientists made a determination of the speed of sound close to Quito (Ecuador) in 1738. There was a particular interest in this measurement at that time because it was thought that the proximity of the Equator and the great altitude would have a major influence on this magnitude. The difference in time between the perceptions of the flash of a gunshot and of the corresponding sound was measured at two different sites. At one of them, Jorge Juan and Louis Godin obtained a value of 341 m/s for the speed of sound, and at the other, Antonio de Ulloa and Pierre Bouguer deduced a value of 348 m/s. Juan and Ulloa published these experiments in their book “Observaciones Astronomicas y Phisicas” (1748). They also presented possible applications of these studies of sound propagation to geometry, navigation, and warfare.

Analysis of Spanish adjectives to develop a Likert scale useful for studies of urban noise annoyance

The present work describes the development and analysis of a Spanish annoyance scale for use in community noise assessments. The use of different descriptors and intervals for different authors prevents comparing studies of assessment of noise reactions. It is not clear how many semantic distinctions can be made to describe subjective reactions to noise. There is also great variability in language use reflecting educational, social class, regional, and subcultural differences. Finally, scaling annoyance responses, when the considered intervals are not equally distributed, may seriously distort results when analyzed with parametric statistics. Using three different questions, almost 400 subjects were asked to rate 25 different Spanish descriptors of annoyance. Our attempt to produce a Spanish standardized annoyance scale with descriptors marking clear semantic distinctions, roughly equidistant from each other, and having wide acceptability is presented here. Taking into account that Spanish is the official...