Eva Escuder Silla

Effect of the estimation of the wall/floor junction type on the acoustic isolation

Deviations between the laboratory measurement and the final in situ measurement, are common in the acoustic isolation. A fundamental difference between both cases is the effect of the lateral flanks. This effect produce that the global acoustic insulation changes substantially. With the standard UNE‐EN‐12354‐1, it can be estimated the effect of the flank, obtaining the vibration reduction indexes and evaluating the insulation of every way. It is also possible to carried out a measurement procedure with the Standard ISO 10848, in it the index is measured and then the index is calculated. This paper shows the differences of results of airborne sound insulation and impact insulation with in situ measurements of the vibration reduction index and the different estimations that the Standard allow. Different unions are studied, and the influence of these in the global result of the insulation is evaluated.

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).

Study in the measurement of noise air insulation in laboratory of the effect in the diffuse field

We can obtain, in a transmission chamber, the air transmitted noise insulation. In the standard 140‐1 the characteristics of these chambers are described. One of these characteristics tries to ensure diffuse field inside these chambers. Nevertheless, we cannot assure an incident angle between 0° and 90° on the test wall, there is a limit angle lower than 90°. In this paper, we study the valuation of the committed mistake by limit angle in transmission chambers. Expressions used for calculating the insulation in transmission chambers are obtained from transmission description in diffuse field, in which case the angle is 90°. In this work, for different materials commonly used in transmission chambers tests, the influence of the indetermination of a mistake and the global mistake evolution with limit angle is studied.

Determination of unknown parameters in impervious layers by inverse method

In this work, a novel procedure is shown for the determination of unknown parameters in impervious layers used in multilayer structures by inverse method and using scale models. Experimental pressure and velocity data are obtained by Nearfield Acoustic Holography (NAH) for the calculation of the transmission loss of the different multilayer structures mounted on the window of a wooden box designed for that end. These data are used as input data in the inverse method. The forecast model of acoustic insulation in multilayered structures used in this work was Trochidis&Kalaroutis model based on Spatial Fourier Transform (SFT). By applying Trochidis&Kalaroutis model and adjusting by numerical methods the variables that define the impervious layers of the system, the values of the unknown magnitudes of the layers are calculated. For validation purposes the results are compared to those obtained with Ookura&Saito model.