Development of an ultrasound level meter for use in occupational safety and health

The widespread use of ultrasound techniques throughout industry causes many workers to be exposed to airborne ultrasound at their workplaces. To measure and assess the exposure to airborne ultrasound at these workplaces, devices are required that allow reliable measurements of ultrasound levels and support occupational safety and health measures. However, the sound level meters available to date do not meet these requirements. Therefore, a research prototype of a sound level meter covering audible and ultrasonic frequencies was developed, paying particular attention to the suitability of the components in terms of their acoustical characteristics (such as directional patterns) in the ultrasonic frequency range. The prototype was tested based on the international standard for sound level meters IEC 61672-1, with extensions regarding the signal frequencies used. The results revealed that the sound level meter developed is suitable for application at most workplaces exposed to ultrasound, as reflected by, e.g., its frequency range (at least up to 47 kHz), upper level limits (up to 160 dB SPL), and measurement uncertainty (k = 2, GUM) of 1.15 dB. The prototype developed allows measurement and assessment of exposure at workplaces for occupational safety and health purposes. Moreover, it can serve as a basis for future developments of commercial ultrasound level meters.