Experimental formulation of four poles of three-dimensional cavities and its application

While the four-pole approach is a very convenient concept in modeling acoustic systems, its application has been limited mainly to systems composed of only one-dimensional (1-D) and lumped parameter elements due to the difficulty in formulating four poles of three-dimensional (3-D) cavities. In this work, an experimental procedure is developed to obtain four poles of a 3-D cavity from the measured pressure response functions. The procedure is validated by comparing the four poles obtained experimentally for a rigid-walled rectangular cavity with those obtained by analytical and numerical procedures. Establishing an experimental procedure for four-pole formulation is significant as it enables application of the four-pole approach to virtually any acoustic systems. The concept of hybrid modeling, which is building the system model by combining experimental, numerical and analytical models, is demonstrated through a simple example as the best application of the four-pole approach.