Jaime Ramis

Noise effects of reducing traffic flow through a Spanish city

Abstract Towards the end of 1999, the building of one of the main communication routes in Spain was finished, the A-3 motorway, which connects Madrid and Valencia. So far, this road was running through the town Motilla de Palancar, province of Cuenca. The opening of the last section of the motorway on 3 December 1999, re-routes all the traffic passing through the town. This study makes a comparative of the noise levels before and after the opening of the motorway that goes through Motilla de Palancar.

New absorbent material acoustic based on kenaf’s fibre

This project has been funded by the Ministry of Education and Science. DG Research (BIA2007-C02-01 y BIA2007-C02-02).

Nuevos materiales absorbentes acústicos basados en fibra de kenaf

This project has been funded by the Ministry of Education and Science. DG Research (BIA2007-C02-01 y BIA2007-C02-02).

The Uncertainty in Absorption Coefficients Measured in Reverberant Chambers: A Case Study

The aim of this work is to study the uncertainties that are present in measurements of the sound absorption coefficients of acoustical materials by means of the determination of the reverberation time (according to ISO 354 [1]). A detailed study of the uncertainty in the measurements of sound absorption coefficients has been performed. As an additional feature we present a representation of the absorption coefficient and its relative uncertainty.

Vibration Reduction Index of a T-Junction With a Flexible Interlayer

This paper describes the procedure followed to evaluate the vibration reduction index for T-junctions with inserted flexible elements and proposes new equations to complement the standard EN 12354-1:2000. The experiment described in this work is based on a 1:3 scale model of a T-junction with a flexible interlayer. It was used to obtain a significant reduction in the cost of the configurations under study. We chose to carry out vibration measurements by near-field acoustic holography (NAH) in order to avoid the risk of accelerometer interference. Flanking transmission was determined for different elastic layers with the objective of quantifying the effect of the flexible interlayer and to compare the results obtained with predictive formulas. The results enabled us to propose new equations to complement EN 12354-1:2000 for the reliable prediction of the apparent sound reduction index. The uncertainty associated with the different average velocity levels is determined according to the Guide for the Expression of Uncertainty of Measurement (GUM).

Road traffic noise barriers based on recycled materials.

One of the main corrective measures taken to reduce environmental noise produced by roads is using sound barriers. However, the construction of miles of noise barriers implies a high cost. One solution to reduce the costs is using recycled materials in the noise barriers, for example, plastic wastes, which has great environmental benefits. According to EN 1793‐1 to 3:1998, the main acoustic characteristics of noise barriers are the sound absorption and the airborne sound insulation. On the other hand, the technical document CEN/TS 1793‐5:2003 gives guidelines for determining the in situ sound reflection index, which is an important parameter because the reflections from the barrier may increase the background noise in the surrounding area. This method has not been validated for noise barriers having a relatively low airborne sound insulation. In this study, sound reflection index using the impulse method is obtained in the laboratory for a wide frequency range. Environmental designs of road traffic noise ...

An inverse method to characterize fibrous sound absorbing materials.

Characterization of sound absorbing materials is needed to predict its behavior. The most commonly used models to do so consider the flow resistivity, porosity, and average fiber diameter as parameters to determine the acoustic impedance and sound absorbing coefficient. Besides direct experimental techniques, numerical approaches appear to be an alternative to estimate the material’s parameters. In this work an inverse numerical method to obtain the porosity, the fiber density, and the fiber average diameter of a fibrous material is described. Using normal incidence measurements of the sound absorption coefficient and then using the model proposed by Voronina, subsequent application of basic optimization techniques allows one to characterize a sound absorbing material. The numerical results agree fairly well with the experimental data.

Acoustic Environmental Monitoring System for Acoustic Maps

In this work, it is developed a data acquisition and analysis system for the monitoring of acoustic environmental noises and the elaboration of dynamic acoustic maps. This project is based on the obtaining of acoustic data in different measure points, and it is formed by a mesh of connections based on GPRS NODES and a Software Server for the administration and control of the data.

Comparison between the marine soundscape of recreational boat mooring areas with that of a pristine area in the Mediterranean: Evidence that such acoustic hot-spots are detrimental to ecologically sensitive habitats

We investigated the potential to use passive acoustics to access the impact of recreational boat mooring areas on ecologically sensitive habitats in the Western Mediterranean. One important consequence of the tourist industry in the region is that it targets the most pristine and ecologically sensitive habitats. Underwater sounds were recorded in mooring areas in Ibiza, Formentera and Tabarca harbors during high use and low use seasons and compared to recordings in the Tabarca Marine Protected area. At each location, we recorded sounds during 20 min at three different sites, for three random sampling times during the day. The percent of time occupied by selected biological (drums and croaks) and anthropogenic sounds (boat and mooring chain noises), and call rates of selected fish sounds were measured and compared among sites and seasons. Biological sounds contributed significantly less to the soundscape in mooring areas during the tourist season, and to the reserve in both seasons. Our study demonstrates ...

Numerical analysis of the vibrational behavior of the moving assembly of a dynamic loudspeaker

This paper describes the process undertaken to analyze numerically the vibrational behavior of the moving assembly of a dynamic loudspeaker with double bottom suspension and in the absence of the above one using the finite element method (FEM). The study focuses on the low frequency range. Model calibration was performed based on experimental measurements of the resonance frequency and diaphragm displacement. The importance of the participation factors associated to the excitation force and the changes produced in these when unbalanced forces are introduced are emphasized. The analysis also provides data to decide on the distance between suspensions, their optimal number of folds and the placement of the lead wires, parameters of great interest on the design of this type of loudspeakers.