Effect of noise on human performance under variable load in a die casting industry--a case study

The manual mode of working in industries is very common in the developing and under developed countries. Many industrial processes have generated high levels of noise and causing physiological effects on operators and thus leading to reduced performance. A survey was carried in various die casting industries to determine the levels of noise. It was found that the levels were in the range of 80-100dB(A). The survey also showed that the effects were more pronounced when the task was conducted under varying load conditions. Keeping this in view the problem was formulated to study whether the level of noise and amount of load has a bearing on human performance. For this purpose, experimental investigations in a simulated environment were carried out. Five subjects, all males and having no experience in the trade were selected for the task. The levels of noise under taken were 80, 90 and 100 dB(A) while the levels of load were 150, 200 and 250 N. A pulse oximeter was used to measure the human performance in terms of heart rate. The data was collected and analyzed on the basis of two factor repeated measure type of experimental design. Results of the study indicated that the level of noise and load both were having statistically significant effect on human performance. However, the interaction of level of noise and load was found to be statistically non-significant. The findings of the present work have been discussed in the light of the previous researches carried out on the topic. Suggestions have been made to reduce the levels of noise as per the recommendations of Occupational Safety and Health Association (1990). It is also suggested that instead of hand operated machines, foot operated versions should be used to reduce fatigue.