Exposure of employees to very high frequencies: laboratory measurements

Many occupational sectors are subject to noise exposure to very high audible frequencies (VHF) or low frequency ultrasound (LFUS): welding, food cutting, cleaning, etc. Although studies on employee exposure to these sound sources have been carried out since the 1960s, the question of the location of the measuring microphone and the representativeness of the measurement remains. As part of a study focusing on the risks associated with exposure to VHF/LFUS, the INRS conducted laboratory experiments on a mannequin to assess the variability of exposure measurements under controlled conditions as a function of microphone location (shoulder, ear entrance, etc.), source frequency and source position in azimuth. Of particular interest was the appropriateness of positioning the microphone at temple level via a dedicated mounting system suitable for use in the field. The findings of this preliminary work will be used to develop a protocol for measuring VHF/LFUS exposure in situ.