Survey of undesirable noises in an industrial clean room

Abstract

In industrial clean rooms, air conditioning systems and other necessary equipment are a constant source of noise. Out of the three clean rooms (X, Y, and Z) managed by us, Room X had particularly annoying noise levels, and required investigation. In this study, surveys are performed to determine how the noise can be minimized: the facilities in each room are investigated, the working environment and personal noise exposure are measured, the noise sources are subjected to frequency analysis, and hearing tools are evaluated to reduce annoyance among clean-room users. The measurement results show that the noise level in room X was more than 5 dB higher than that in rooms Y and Z. The frequency analysis results show that the dominant frequency spectrum of the fan filter unit (FFU) operating noise is around 100 Hz, and that of the air blowing noise is in the high frequency range above 10 kHz. Finally, hearing tools (noise-canceling earphone and earplugs) are distributed to workers in Room X, who rank their effectiveness. The results show that noise-canceling earphones are preferred, although no statistically significant differences are obtained. Consequently, the work environment is effectively improved.