Experience predicting structure-borne noise within a prototype rectangular acoustical enclosure

Approximately 10 years ago a large rectangular enclosure was designed and constructed using a steel super-structure and sand-filled, double-panel plywood walls. The enclosure is approximately the size of a transportation vehicle passenger cabin (1.85 m by 1.05 m by 1.05 m). The enclosure was built such that any of the walls could be replaced with more realistic structures such as vehicle panel constructions. The enclosure has been modified many times to accommodate various experimental apparatus. In this paper, the design of the enclosure will be described and some of the original data used to verify its characteristics will be shown. Recently, the enclosure has been modified to resemble structure (f) described by the Structure-borne Noise Committee of INCE-USA. One wall of the structure has been replaced by a simply supported panel. Experimental results have been compared to analytical and numerical predictions for both internal acoustic excitation and mechanical excitation of the panel. These results will be discussed. In addition, an effort has been made to design a small version of this enclosure which could be used for round robin testing. Preliminary results of this effort will also be discussed.