SPATIAL VARIABILITY OF NOISE GENERATED BY A SELF-PROPELLED COFFEE HARVESTER IN AN OPEN AREA

ABSTRACT Despite the advantages in production, mechanization may expose workers to high noise levels in the work environment, which is considered one of the main causes of work-related hearing loss. In this sense, this study aimed to analyze the spatial variability of noise generated by a self-propelled coffee harvester in an open area to define safe zones for operators and workers involved in coffee harvesting activities. The noise source used was an Electron Auto TDI self-propelled coffee harvester (model MWM D229-4), with a cabin manufactured in 2012 and a 67-hp 4-cylinder engine, working at 1200-rpm rotation. The noise level was measured by a digital decibel meter at points distributed within a regular 2.5 x 2.5 m sampling mesh (32.5 x 35.0 m area) surrounding the harvester in operation, which was configured according to the regulatory standard. Noise level spatial dependence was analyzed through geostatistics, characterizing structure and magnitude, and mapping spatial variability. Results showed that noise levels were above the limit established by relevant legislation (i.e., 85 dB), both for operators and employees at a distance of about 5.5 m from the generating source.

摘要 尽管机械化生产具备诸多优势，但却可能使作业人员暴露于作业环境中的高强度噪声之中，而此类噪声被认为是职业性听力损失（work-related hearing loss）的主要诱因之一。有鉴于此，本研究旨在分析露天场地中自走式咖啡采收机（self-propelled coffee harvester）产生的噪声空间变异特性，以划定咖啡采收作业相关操作人员及作业人员的安全区域。本次研究所使用的噪声源为Electron Auto TDI型自走式咖啡采收机（型号MWM D229-4），其驾驶室生产于2012年，搭载67马力四缸发动机，作业转速为1200转/分钟。按照监管标准设置采样方案，采用数字声级计（digital decibel meter）对作业中的采收机周围的规则2.5×2.5米采样网格（覆盖32.5×35.0米区域）内的各测点噪声级进行测量。通过地统计学（geostatistics）方法分析噪声级的空间依赖性，对其空间结构与强度进行表征，并绘制空间变异分布图。研究结果显示，在距噪声源约5.5米的范围内，无论是操作人员还是其他作业人员所处区域的噪声级均超过了相关法规规定的限值（即85分贝）。