[Assessment of the impulse noise attenuation by earplugs in metalworking processes]

The aim of the study was to answer the question of whether earplugs provide sufficient protection in the exposure to impulse noise generated during metalworking processes.

The noise generated by die forging hammer and punching machine was characterized. Using an acoustic test fixture, noise parameters (LCpeak, LAmax) under 24 earplugs, foam, winged and no-roll, were measured. Octave band method was used to calculate values of LAeq under earplugs.

It was found that in the case of punching machine the exposure limit value of A-weighted noise exposure level, normalized to an 8-h working day (LEX, 8h = 94.8 dB) of noise present at the workstation, was exceeded, while in the case of die forging hammer both the exposure limit value of this parameter (LEX, 8h = 108.3 dB) and the exposure limit value of peak sound pressure level (LCpeak = 148.9 dB) were exceeded. The assessment of noise parameters (LCpeak, LAmax, LAeq) under earplugs revealed that the noise attenuation can be insufficient, sufficient, or too high.

Earplugs can be suitable hearing protection devices in metalworking processes. Of the 24 earplugs included in this study, 9 provided appropriate noise attenuation in the case of tested die forging hammer and 10 in the case of tested punching machine.