E. Gaja’s research while affiliated with Polytechnic University of Valencia and other places

Traditionally, road traffic has been considered the main noise source in urban and interurban areas. As a consequence, governments have developed some new regulations to assess and control these constantly growing noise sources [1]. At the same time, numerous research groups have analysed and studied the main characteristics of new models of vehicles as a noise source and how technological improvements can reduce the overall levels emitted by road traffic, considered as a linear source. However, the sound effect of mechanical wear of vehicles has not been deeply studied, neither analysed. This paper aims to analyse the evolution of noise emissions of different vehicle types over time, based on the results of real technical inspections of vehicles. Since August 2004, the Technical Inspection of Vehicles Centres (ITVs) located in the Valencian Region have been recording the noise emissions levels of millions of vehicles in static tests, in accordance with Decree 19/2004 [2] passed by the Consell de la Generalitat (Regional Council). This extensive data logging provides a great opportunity to evaluate sound characteristics of the vehicles of this region over the last 7 years. Therefore, in this paper, sound trend of different types of vehicles depending on the passing of the years is analysed. The purpose of this study is to determine the evolution of the sound level of vehicles over time and the influence on traffic noise prediction models used to develop noise maps.

This work summarizes several years of measurements of the main noise sources present in large populations, specially the noise produced by the traffic in the city of Valencia. The study includes one-week monitoring in the period between the years 2012 and 2014 in three different types of scenarios (heavy, medium and low traffic). The aim of this work is firstly to determine the most representative measurement day under several approaches related to the type of day (working day, non-working day or full week), and to the different periods throughout the day (night, day and evening).

The standard method for computing noise contours around civil airports is SAE-AIR-1845 (FAA Integrated Noise Model, European ECAC-CEAC Doc. 29). It is subject to the inaccuracies implicit in the model as well as those caused by erroneous or imprecise input data. Regarding the latter, the existing errors and/or uncertainties, may be amplified in the output results, to a greater or lower extent, in some cases offering unreliable predictions.In order to study this phenomenon, the Institute of Sound and Vibration Research (ISVR – Southampton) carried out a theoretical sensitivity analysis based on the segmentation technique, regarding the input parameters of the SAE-AIR-1845, and obtaining the input variables of the model, the variation of which implied greater changes in the output variables. The results were validated by using the FAA Integrated Noise Model Version 6.0 software, based on the aforementioned document. It has been revealed that the model has a greater sensitivity to factors that modify the flight path, and a lower sensitivity to the other parameters. Thus, an error greater than 10% in the variable “gross weight” offers an additional error of between 3 and 7 dB. However, parameters such as the ID of the flaps hardly modify the results obtained for the least favourable case by 1 dB.As a result of this research, the sensitivity of the model was quantified for each of the input parameters (taken alone and also in interaction with other parameters), and criteria for the minimisation of global error, resulting from uncertainties in the input parameters, were stated.

This paper summarises 5 years of continuous noise measurements carried out at one of the most important squares in Valencia (Spain). The chosen square is a clear hotspot for traffic noise in a large city. The aim of this study is to determine the appropriate measuring time in order to obtain a 24-h noise level suitable to represent the annual equivalent level. Our findings allow us to reach a number of conclusions in terms of the most suitable urban traffic noise measurement techniques. A random day strategy for sampling is found to give a more accurate representation than a consecutive days strategy. If the sampling strategy involves measurements on randomly-chosen days, then at least 6 days should be used.

In this paper a resume of six years of working and researching on the evaluation of noise pollution in 56 cities of the Valencian Community (Spain) is presented. The main source of this noise pollution is due to urban traffic. The aim of this paper is to establish the possible correlation between the noise level and the official register of citizens in those cities, which are from a wide range of the population; from 1110 to 750000 inhabitants. This could be a good method to obtain conclusions whether a city has the right level of noise according to its population or, on the other hand, whether the noise level is too high or too low.

This paper is concerned with the description of various factors, such as velocity, gears, and type of vehicle affecting the power level of a vehicle noise; a resume of this dependence will be offered. This work has been done in the Universidad Politecnica de Valencia (Spain) by the Laboratorio de Ingeniera Acoustica within a Thesis Project, with the aim to develop a predictive mathematical model of the urban traffic noise. Measurements were taken with an analyst Bruel mod. 2236, which enables one to obtain power levels in third octave bands by a real‐time spectral analysis. The measurements being used are extensively explained in this paper, in particular that special care was taken to avoid noise from other sources that could interfere with the results. The reason why the power level was chosen as the first stage of this study of traffic noise, starting from the single vehicle as the point source, was to comply with the methodology established in the second part of standards ISO 9613, leaving for a second stage the propagation of the urban traffic noise. The final results show the great correlation between speed of the vehicle and power level.

This paper sums up the methodology used and the plan of action taken for verification of the ‘heat island’ in the city of Valencia. At the same time it attempts to outline the role that green areas play in the distribution and pattern of urban temperature, thus constituting basic data for ‘ecological engineering’ in modern city planning.

The City of Valencia has approximately 700 000 inhabitants. Due to this large population, the city is subjected to heavy traffic, and, as a consequence, high acoustic pollution. The Townhall of Valencia is very worried about this acoustic pollution and has commissioned the Laboratory of Acoustics in the Universidad Politecnica de Valencia to work on various projects within the city. Due to the work the department has carried out on behalf of the Townhall of Valencia, it has gained experience measuring with the sonometer. An efficient way of measuring noise within the city that avoids wasting long periods of time has been developed. Continuous 24‐hour measurements have been taken by sonometers located in different stations spread out around the city and controlled by the Townhall. With these measurements a method that indicates when to measure, in the morn‐ ing, afternoon, and at night, as well as the exposure time, has been designed. Other parameters, such as characteristics of the traffic, types of stree...