Analysis of the psychoacoustic parameters in agricultural tractor cabs

At the operator station of agricultural tractors, safety and comfort issues are both important aspects to be taken into account to prevent health risks and assure high work performance. Referring to noise, the reduction of exposure levels and the improvement of the sound quality in order to decrease annoyance are both key elements to reach the above targets. Nowadays, almost all the new tractor models have a cabin designed to decrease noise exposure levels well below the permitted limit values in different working conditions but this does not mean that comfort conditions are reached. The aim of the research was to evaluate how the operating conditions of different agricultural activities affect the main psychoacoustic parameters, namely loudness, sharpness, roughness, and fluctuation strength. Field tests were carried out (binaural recordings) on four tractors with different arrangements but similar mechanical power, with the tractors operating in various conditions in term of travelling surface, and type of work (ploughing, harrowing and transfer on different surfaces). The performance of every psychoacoustic parameter was investigated using different statistical methods in order to remove possible redundancies in the number of variables and evaluate whether the variance of the remaining set of parameters was in fact correlated to variations in operating conditions or due to chance.