Impulse noise in industrial plants: statistical distribution of levels.

Impulse noise generated by industrial machines and occurring at a workplace is a cause of substantial hearing loss in workers. The paper presents data on workplace impulse noise, recorded in three plants of the machine industry. The data were collected in drop-forge, punch-press and machinery shops. The results of the measurements are shown as cumulative relative frequency distributions of the C-weighted peak sound pressure level, L(Cpeak), the A-weighted maximum RMS sound pressure level (SPL), L(Amax), and the A-weighted sound exposure level, L(EA) of isolated acoustic impulse noises. The survey shows that in the drop-forge shop over 90% of acoustic impulses generated by hammer strikes exceed permissible levels of L(Cpeak) = 135 dB and L(Amax) = 115 dB. In the stamp-press shop, only 10-20% of impulses generated during the technological process exceed maximum permissible levels.