Acoustic design of a best-in-class drill rig cabin

Drill rigs used for percussive rock drilling are sources of intense high-frequency noise. A drill rig manufacturer targeted the in-cabin A-weighted noise level at the operator's position during drilling to be less than 75 dB. The target sets very strict demands on the noise reduction capability of a cabin. As is well known, considerable modifications to a final product are very difficult. Therefore, the cabin acoustic design process, described in this paper, was started eighteen months before the manufactured cabin was available for assessment. Thanks to the early, proactive start, the result is a cabin with an excellent acoustic performance and the target was successfully met. The most critical cabin component group is glazing, which covers some 40 % of the outer surface of the cabin. Much effort was put on simulation-based acoustic design, optimization and selection of thick, multi-layer laminated glasses. Another critical factor emphasized is control of leakage, especially avoidance of imperceptible leaks in door seals, plate junctions etc. Due to the harsh working environment, the possibility to use porous materials for enhanced absorption is very limited. Numerical simulations using SEA and experiments conducted in various phases of the process are described. Experimental results of the final product are compared to early predictions and updated simulations. Uncertainties arising from incomplete data available in the early design stages, rig operating environment as well as from the methods themselves are discussed.