Técnicas avanzadas de medida en intensimetría acústica para la caracterización de materiales aislantes

Abstract

Por último, el procedimiento ideado permitirá futuros desarrollos en el campo de la vibroacústica, tales como, la aplicación del principio de reciprocidad y la determinación de la impedancia acústica de materiales por técnicas de intensimetría acústica. ABSTRACTThe measurement rate of acoustic reduction (R) in an insulating material is determined in special designed enclosures according to UNE EN ISO 140-1 standard. The construction of a testing room that complies with the standards requires a significant financial investment, that too often can not be provided by general machinery manufacturers. The outdoor machines have to be designed considering the noise emission limits established in the European Directive 2000/14, making the installment of insulating materials in enclosures of machines necessary.Suppliers of insulating materials for industrial use does not normally provide the insulating properties of their products, which are often obtained from rock wool, polyethylene, polyurethane, synthetic rubber, etc. It is difficult to test these materials that are characterized by low density surface in a room standardized test procedure that is based on the measurement of sound pressure.The main problem is getting the validation of the measurement when the rate of acoustic reduction is relatively low, as in the case of materials mentioned above.An alternative procedure is proposed in this Doctoral Thesis based on the measurement of sound intensity. The vector nature of this parameter allows just the flow of energy through a given surface to be measured. The validation of the measurement is achieved with the highest degree of accuracy by applying the criteria included in the standard UNE EN ISO 9614. A steel plate 6 mm thick incorporated with a sound source for amplification of a pink noise signal is designed for carrying out the tests.