C. Asensio

Reduction in Calculated Uncertainty of a Noise Map by Improving the Traffic Model Data Through Two Phases

The influence of applying European default traffic values to the making of a noise map was evaluated in a typical environment like Palma de Mallorca. To assess these default traffic values, a first model has been created and compared with measured noise levels. Subsequently a second traffic model, improving the input data used for the first one, has been created and validated according to the deviations. Different methodologies were also examined for collecting model input data that would be of higher quality, by analysing the improvement generated in the reduction in the uncertainty of the noise map introduced by the road traffic noise emission.

Design of a noise action plan based on a road traffic noise map

According to European Directive 2002/49/CE, EU state members had to compile a strategic noise map no later than 30 June 2007 and a corresponding action plan no later than 18 July 2008 for all agglomerations with more than 250,000 inhabitants and for all major airports, roads and railways. A study on environmental noise was thus conducted for the city of Palma de Mallorca (Spain) using a commercial noise prediction package. The noise level assessment reveals a troublesome situation that requires an urgent noise action plan. In this report, various noise mitigation measures are analysed considering not only the reduction of noise and the number of people that can benefit from these measures, but also the net monetary benefits generated. Given the possible options, it is clear that to achieve the best long-term solution, global noise abatement measures (i.e., traffic management) and local measures (i.e., noise screens) should be combined.

Airport noise insulation programs: The Spanish case

Noise pollution around airports is one of the most important problems in environmental acoustics. The incessant development of modern societies is continuously increasing the demand for air transport, and airports have to grow to adapt their operational capacity to the new requirements. On the other hand, the economic activity related to airports is closely linked to the expansion of built-up areas around them. Consequently, two completely incompatible land uses are forced to coexist, causing airport capacity to remain limited while the inhabitants do not cease to be annoyed by aircraft noise. Although there are several international initiatives setting the focus on the reduction of noise at the source, people living in residential areas around airports need urgent solutions. Among others, the implementation of sound insulation programs is one of the most widely-adopted solutions worldwide, as it allows a reduction of sound levels in the interior of dwellings, while the operational capacity of the airport remains unaffected. The definition and application of a sound insulation program is a very complex process that needs to manage several opposing factors: health, annoyance, airport capacity, economic costs of insulation measures… In this paper we describe the case of Spanish airport insulation programs. We set the focus on a concise description of the full process, from the creation of noise maps, to the checking of installed soundproofing measures, as carried out by the Spanish administration. As a result of this process, thousands of dwellings and houses have been acoustically insulated to meet indoor noise comfort criteria in Madrid, Mallorca and Malaga airports, among others.

Assessment of Noise Exposure During Commuting in the Madrid Subway

Because noise-induced hearing impairment is the result not only of occupational noise exposure but also of total daily noise exposure, it is important to take the non-occupational exposure of individuals (during commuting to and from their jobs, at home, and during recreational activities) into account. Mass transit is one of the main contributors to non-occupational noise exposure. We developed a new methodology to estimate a representative commuting noise exposure. The methodology was put into practice for the Madrid subway because of all Spanish subway systems it covers the highest percentage of worker journeys (22.6%). The results of the application highlight that, for Madrid subway passengers, noise exposure level normalized to a nominal 8 hr (LEx,8h-cj ) depends strongly on the type of train, the presence of squealing noise, and the public address audio system, ranging from 68.6 dBA to 72.8 dBA. These values play an important role in a more complete evaluation of a relationship between noise dose and worker health response.

Aircrafts' taxi noise emission

An investigation has been conducted, with the objective of creating a database of inputs that can be used with noise prediction software, to evaluate noise of aircraft taxing movements and community noise exposure levels. The acoustic consultant can use these data with any of the software packages, to simulate taxing, by moving point source. ISO 3744 Standard is used, to estimate sound power levels emitted by a noise source and helps in describing a procedure based on sound pressure level measurements in a free field over a reflecting surface. The main steps that are involved in the procedure, include a measurement surface grid needs to be defined, to envelope the noise source and linear averaged third octave band spectra needs to be measured for all microphone locations.

Communicating airport noise emission data to the general public

Despite the efforts that the aviation industry has undertaken during the last few decades, noise annoyance remains high, partly because of the continuous transport demands of modern societies and partly because of changes in citizen expectations and their growing environmental concerns. Although modern aircraft are considerably quieter than their predecessors, the number of complaints has not decreased as much as expected. Therefore, the aeronautical sector has tried more sociological and/or psychological strategies to gain acceptance through awareness and community engagement. In this regard, noise communication to the public is crucial for managers and policy makers. Noise information is a difficult technical topic for non-experts, which is an issue that must first be addressed to take advantage of the new possibilities that have recently been opened by the internet and information and communication technologies. In this review paper, we have compiled the literature that shows the increasing importance of communicating noise information from aircraft and the variety of indicators used to communicate with the public. We also examined the methods of representing noise data, using visualization strategies, and new tools airports are currently using to address this communication problem.

A Review of Non-Acoustic Measures to Handle Community Response to Noise around Airports

It seems obvious that the noise levels in local communities surrounding airports influences the level of acceptance of an airport. What is not so evident is the effect of non-acoustic factors that increase the societal rejection, like the lack of sensitivity and empathy from the authorities and airport managers, the lack of trust in them, the lack of information and transparency, the perception of being excluded from the decision making and so on. Complementary to the traditional strategies based on the reduction of noise exposure, a community engagement and involvement approach brings new possibilities to manage noise around airports, trying to exploit the non-acoustic factors that have negatively affected the community response. Building trust among the stakeholders is a key factor in this strategy, and it must be based on a long-term, honest, and transparent two-way communication. In the last decade, the huge growth of the information and communication technologies has opened new opportunities that the aviation organizations and stakeholders are starting to explore in depth trying to reduce the degree of rejection of the airport, which may compromise the utilization of existing and future infrastructure. In this review, we make a short introduction on aircraft noise health effects, to focus annoyance and the influence that non-acoustic factors on it. Then, we describe the basis of community engagement as a parallel approach to mitigate noise issues around airports, setting the focus on the noise metrics and the involvement techniques that must be implemented to engage the community.

Platform for on-board real-time detection of wet, icy and snowy roads, using tyre/road noise analysis

In this paper, a new approach capable of detecting water, ice and snow on the road surface is shown, focusing on the hardware needed for the practical implementation. Proposed platform uses a simple microphone and a general purpose microcontroller. The system is tightly integrated with vehicle ECUs (Electronic Control Units). A CAN bus allows it to read some of the variable dynamics provided by the sensors already installed in virtually every motor vehicle. Detector results are also published through the CAN bus to be displayed on the vehicle console and to be used by other ECLs. Proposed system is simple, cheap and easy to install. Initial tests for the wet/dry detector classes have shown a very high success rate.

An intelligent thrust reverse noise detector

An intelligent thrust reverse noise detector is presented in this paper (TREND).A first detector is customized for the detection of landing sound events. When one of those events is detected, a second detector is triggered to detect thrust reverse. In the case that both events are detected, each of them have to be classified in two separate block. If the first events is classified as landing, and the second one as thrust reverse, the system identifies the activation of thrust reverse. The detection is based on thresholds applied to the sound power level (instead of sound pressure level in the traditional approaches) time histories, which are estimated using a microphone array and an inverse sound propagation model. This approach has worked well, as the estimation of sound power level enhances the sound events and their separation, even if landing and thrust reverse are close to each other. The classification is implemented through pattern recognition techniques, which reduces the number of false positive in the detection stages. The results obtained in Madrid-Barajas airport through the implementation of the methodology in this TREND tool are promising with error rates lower than 10%.

Personal computer and frequency analyzer measure reverberation time

This paper shows how a frequency analyzer (such as Bruel and Kjaer’s Model 2144) can be used to perform reverberation time measurements with the help of some extra software. Although a particular solution is presented, the concept can be applied to any frequency analyzer that has a programmable interface. Bruel and Kjaer’s Model 2144 is a powerful frequency analyzer, but it does not measure reverberation time. On the other hand, the analyzer has a programmable interface (GPIB) that permits us to control the instrument from a personal computer. This paper shows how a software application has been developed that gives the B&K2144 connected to a computer, the capacity of measuring reverberation time. The application has been developed using LabVIEW and it makes reverberation time measurements easy and reproducible.