On the use of paintings and tapestries as sound absorbing materials

Churches and other buildings listed as cultural heritages often require acoustical treatments in order to control reverberation time and other acoustical parameters. However, due to their high artistic value the use of conventional sound absorbing materials is generally forbidden or, at least, highly discouraged. Conversely, the use of paintings and tapestries is often more tolerated even though their acoustic effect needs to be carefully evaluated as it largely depends on the type of painted surface (wood, canvas) as well as on the type of painting. The results of the on-site and laboratory measurements of absorption coefficients of different types of paintings and tapestries are discussed. Finally, in order to obtain improved absorbing characteristics, the combined effect of painted canvases covering porous materials is investigated. Results show that, in agreement with theoretical models, impermeable treatments (resulting from the use of acrylic or oil colours) mostly affect high frequency absorption