Impulse noise measurement in view of noise hazard assessment and use of hearing protectors.

Experience shows the occurrence of situations when the measurements of impulse noise parameters are made with measurement equipment unsuitable for such conditions. The results of using such equipment were compared with the results of using equipment with a sufficiently large upper limit of the measurement range. The analysis was carried out on the example of noise generated during shots from a Mossberg smooth-bore shotgun and AKM rifle, as well as produced in the forge. The use of the unsuitable equipment allowed to indicate the exceeding of the exposure limit value of the peak value of the signal (LCpeak), but this is not always possible when determining the energy properties of the signal (LEX,8h). While the inadequate properties of the measurement equipment will generally not prevent the conclusion that noise in a particular workplace is hazardous to hearing, the results of measurements cannot be used to select hearing protectors.

[ASSESSMENT OF THE AUDIBILITY AREA OF AUDITORY DANGER SIGNALS PRODUCED BY INDUSTRIAL TRUCK]. / OCENA OBSZARU SLYSZALNOSCI DZWIEKOWEGO SYGNALU BEZPIECZENSTWA EMITOWANEGO PRZEZ WÓZEK JEZDNIOWY.

BACKGROUND: The aim of the study was to answer the question what is the audibility area of auditory danger signal emitted by an industrial truck in the noisy environment. MATERIAL AND METHODS: The sound pressure level of the signal produced by the truck horn was measured in 12 directions around the truck, at a distance of 2 to 10 m. It was analyzed, in which places around the truck, auditory danger signal emitted by this truck can be reliably recognized (according to PN-EN ISO 7731). The analysis included 2 types of masking noise. RESULTS: The calculated audibility area in the presence of one type of the noise is about 2-8 m in front of the truck and up to about 3 m on both sides of the truck. Furthermore, itis audible from the rear of the truck, in the range of about 1.5-10 m and 3-7 m, respectively onthe right and left axes of the truck. In the case of high-frequencynoise, despite of its.higher A-weighted equivalent sound'pressure level (12.5 dB), the audibility area is not significantly different. CONCLUSIONS: The presented method of analysis allowed to determine the audibility area of auditory danger signal in the case of considered industrial truck, at the specific workplace. This method can be used in the future to evaluate any auditory danger signal at the workplace, where noise is present. The caselstudy showed that it is possible to encounter a situation where the use of hearing protection devices at the workplace cannot affect the audibility area.

[Assessment of the impulse noise attenuation by earplugs in metalworking processes]. / Ocena ograniczania halasu impulsowego przez wkladki przeciwhalasowe podczas obróbki metalu.

BACKGROUND: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.