Estimation of acoustic and elastic properties of plastic foam using acoustic-to-frame coupling

Synthetic partially reticulated polyurethane foams are deployed for many situations for noise and vibration control. So understanding the behaviour of these foams when exposed to acoustic and/or mechanical waves is essential. Much progress has been made through identification and non-acoustic measurements of parameters introduced in the seminal works by Biot and, subsequently, by Allard, that describe the acoustical and elastic properties. Conversely, these parameters can be estimated from measurements of vibroacoustical responses. In principle measurements of acoustic-to-frame coupling should be more effective than measurements that focus on either acoustic or frame behaviour separately. This idea has been pursued in many papers co-authored by Walter Lauriks and Jean- Francois Allard. This paper describes recent demonstrations that pore-related and elastic parameters of air-saturated plastic foam can be estimated from data obtained by conjunctive use of microphones and a laser Doppler vibrometer.