## ABSORPTION MODELLING OF MULTILAYER SYSTEMS

David Oliva, Henna Häggblom, Valtteri Hongisto

Indoor environment laboratory,

Finnish Institute of Occupational Health

Lemminkäisenkatu 14-18B, 20520, Turku, Finland

david.oliva@ttl.fi

The aim of this paper is to validate a prediction model able to calculate the absorption coefficient of multilayer systems at normal incidence. The model is based in the calculation of the system's impedance, from the individual impedances of each layer. The system can be build up from many different layer types, like porous materials, tight panels and tight foils, thin and thick perforated panels, and air gaps. The validation of the model was done for about 200 different systems. The accuracy in the absorption prediction was ∆α=±0.1 for most of the studied constructions systems, in the frequency range 100-3150 Hz.