A practical impedance tube method to estimate the normal incidence sound transmission loss of double wall structureNoiseCon (2011)
AbstractThe objective of this paper is to propose a practical impedance tube method to optimize the sound transmission loss of double wall structure by concentrating on the sound package placed inside the structure. In a previous work, the authors derived an expression that breaks down the transmission loss of a double wall structure containing a sound absorbing blanket separated from the panels by air layers in terms of three main contributions; (i) sound transmission loss of the panels, (ii) sound transmission loss of the blanket and (iii) sound absorption due to multiple reflections inside the cavity. The sound transmission loss contributions of the blanket can thus be estimated from three acoustic measurements using impedance tube techniques: two reflection coefficients at the front face and the rear face of the blanket placed in specific positions characteristic of its position inside the double wall structure and its sound transmission coefficient. The method is first validated in the case of an aeronautic-type double wall structure filled with a 3.5 inch fiberglass. Next, it is applied to a multilayer sound package with a particular focus on the interlayer-interface conditions.
Publication DateSummer July 27, 2011
Citation InformationOlivier Doutres and Noureddine Atalla. "A practical impedance tube method to estimate the normal incidence sound transmission loss of double wall structure" NoiseCon (2011)
Available at: http://works.bepress.com/olivier_doutres/26/