Testing of non-traditional acoustical materials

New materials, such as bottle caps and egg cartons can be used to build an echo-friendly acoustical room for increasing speech intelligibility and also for obtaining better conditions in multimedia studios. Unrecyclable bottle caps can play the role of scatterers. The reflection and absorption coefficients of bottle caps vary according to their diameters and position and thus have a great effect on the reverberation time. Egg cartons have bubbly shape that helps to scatter the sound waves and redirect them so they may help as diffusers. Reflection and absorption coefficients for these non-traditional acoustical materials are measured using the standing wave tube method. The reverberation time method gives the average value of the absorption coefficient. From the obtained results, the frequency ranges for the proper use of these materials to fulfill the desired acoustical quality are discussed.