Use of the Sound-intensity Method to Identify Acoustic Leakages from Off Highway Machine Cab

The operator station or “cab” in off Highway equipment plays a critical role to provide a comfortable environment for the operator. The cab interfaces with several elements of the off-highway equipment which can create gaps and openings. These openings have the potential for acoustic energy leakage, ultimately increasing sound within the cab. During machine operation, noise generated around the cab conducts inside through these leakages resulting in increased sound levels. Acoustic leakages are among the key noise transfer paths responsible for noise inside the cab. Therefore, before considering noise control treatments it is best to first identify and minimize any leakages from joints, corners, and pass-throughs to achieve required cab noise reduction. In this effort the sound intensity technique is used to detect the acoustic leakages in cab. The commercial test system is used for measuring the sound intensity field over objects. For the cab, an acoustic source is used inside the cab as a known energy source and the intensity levels are measured outside the cab. The test is conducted in a semi-anechoic chamber. Each external surface of the cab was scanned with a Sound-intensity probe and the leakages on each surface are detected individually. The results from this test will be used to reduce the leakages, eventually reducing the noise level inside the cab.