Noise intensity and its impact on the perception and concentration level among forest harvesting workers in industrial forest plantation, North Sumatera, Indonesia.

Noise has the potential to affect the comfort and health of workers. The objective of this research was to find out the effect of noise caused by the timber harvesting process using chainsaws on the concentration of workers in an industrial forest plantation. This experimental study included 20 respondents which consisted of 10 chainsaw operators/helpers and 10 non-chainsaw operators. All respondents were exposed to the sound of a chainsaw in three different conditions (idle, half gas and racing conditions) with and without personal protective equipment (PPE). The sound intensity produced by the chainsaw and the noise received by the respondents were measured using a sound level meter. Respondents' perception toward noise was recorded using a Likert scale. Respondents' concentration level was assessed by giving 25 math-questions to be answered within 10 minutes. Wilcoxon sign rank test was used to analysed paired data. The average sound intensity received by respondents' left and right ears were lower than the average sound intensity produced by the chainsaw. The use of earmuffs leads to better perception towards noise when compared with the use of earplugs and the absence of any PPE. The Wilcoxon test result showed that noise did not have significant impact on the concentration level of chainsaw operators, whilst the contrary result is true for non-chainsaw operators. The research indicated that although the noise produced by the chainsaw machine was considered noisy for both chainsaw operators and non-chainsaw operator, it did not have a significant effect on the concentration level of chainsaw operators and only affected the non-chainsaw operators. Therefore, given that the non-chainsaw operators were still affected by the noise, noise control measures are still needed to ensure occupational safety and health for the workers.