Implementation of a filter for active noise cancellation in earmuffs for agricultural tractor operations

Abstract

The implementation of agricultural mechanization is of paramount importance in modern agriculture, providing the replacement of manual and animal work with the aid of modern machines, contributing to an increase in productivity in crops of increasingly larger areas. However, the use of these technologies can bring some inconvenient factors from an ergonomic point of view. Machine operators, for example, are exposed to high noise levels from tractors. Its harmful effects on health are not limited to hearing alone, but can also cause emotional, cardiovascular and fatigue disorders. There are two methods for noise attenuation: The passive method, which consists only of a physical barrier between the listener's ear canal and the external environment, and the active method, which is based on electronic equipment capable of generating a signal that the phenomenon of destructive wave interference. Agricultural operators often use passive noise mufflers which have the disadvantage of attenuating all sounds indiscriminately, thus limiting the operator's auditory perception. In this context, this work proposes an implementation of active noise cancellation that cancels only noise, allowing other ambient sounds to be heard normally. The work developed is of an experimental nature, where a noise source in an agricultural operation was analyzed, which was used as an input signal for the construction of the filter and simulation. The filter was able to perform active noise cancellation using the LMS and NLMS algorithms, but the NLMS presented better results.