Investigation on the Applicability of an Active Noise Control System in the Tractor Cabin Under Controlled Workload Conditions

The reduction of the noise emissions in working environments was strongly improved by the active noise control technology (ANC), a system capable to create an interference disruptive to the (primary) noise by means of the emission of a noise, exactly specular (secondary), electronically generated by loudspeakers suitably controlled by a control unit. Such a technology should be capable to generate a "quiet zone" around the driver's head, reducing the auditory distress, unlike the common passive techniques based on the application of sound-absorbing and sound-insulating materials to the cab's components. CREA conducted research with the aim of evaluating the efficiency of a system for the active control of the noise present inside the driver's cab of a medium power tractor in order to reduce the operator's exposure and to develop the system itself, in its hardware and software components, to make it effective, versatile, and easy to install. The ANC system presented in this study aimed at integrating the action of passive noise-control systems and increasing the level of comfort and health safeguard. The noise level in the cab was measured all along the engine working range represented by the characteristic curves of torque and power. This method allows to reliably compare noise measurements with and without the ANC system. The results indicated that the ANC system can reduce the equivalent level of acoustic pressure in the entire working range of the engine, with major effect under conditions of heavy engine's workload.