Experimental investigation on the acoustic behaviour of a small tractor cabin

The quality and acoustic comfort of agricultural tractor cabins are nowadays highly valued by the market. For this reason, tractor manufacturers are more and more interested in improving the behaviour of their vehicles also from an acoustics point of view. A tractor cabin is an unusual environment, with a space mainly developed in the vertical direction, characterised by a relatively small volume of air and surrounded by windows, which can be considered as large reflecting surfaces. This feature causes strong standing waves that, when coupled with an acoustic source, can generate high sound pressure levels resulting in reduced comfort for the driver. This paper investigates, through measurements and simulations, the low frequency acoustic behaviour of a small tractor cabin. The technique adopted for the measurements is based on a multiple transfer function analysis. Measured frequency response functions are processed for the cabin's acoustic mode parameters. The results of the experiments are validated through a finite-element model allowing the reconstruction of the sound pressure contours inside the volume and further analyses.