[assessment of the Audibility Area of Auditory Danger Signals Produced by Industrial Truck].

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.