Title: Damping out booming noise
text: NVH improvement techniques are gaining traction with the goal to improve the quality perception of off-highway equipment performance and operator comfort. As NVH gains importance in the quality of off-highway machine performance and operator comfort, it is essential to understand every aspect of the machine noise and its annoyance effect on the operator, then reduce the noise to a level that does not affect comfort and performance. Booming noise-a low-frequency NVH phenomenon below 200 Hz often described as a continuous bass drum roll, distant thunder sound, or a deep resonant sound like an explosion-is a major concern in off-highway machines. The booming noise in off-highway machines can be caused by a combination of factors: the low natural frequencies and damping of the large panels of machine cabs; the low acoustic modes of the cab cavity; low-frequency excitation into the cab from machine noise sources such as engine, exhaust, cooling fan, etc.; and low frequency excitation to the machines from machine work tools and ground interaction inputs (tire lug, road profile, etc.).