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The case for ultrasonic measurements

Mobile ultrasound level meter for practical use in occupational health and safety

PTB-News 1.2018
Especially interesting for

occupational health and safety activities in working environments involving ultrasonic technologies

In cooperation with the Institut für Arbeitsschutz
(IFA) of the Deutsche Gesetzliche
Unfallversicherung (DGUV),
the prototype of a portable measuring
system for airborne ultrasound has
been developed at PTB. It will allow the
determination and assessment of potential
workplace risks represented by
widespread ultrasonic machines which
can generate very high sound pressure

The prototype of the ultrasound level meter consists of a notebook, an analog-to-digital converter, a power module, a preamplifier and a 1/4-inch condenser microphone cartridge.

Ultrasound is an increasingly used technique in various areas such as welding, cleaning or cutting. When using ultrasound, the sound pressure levels can sometimes be very high. According to the German regulation on protection against noise and vibrations at the workplace (Lärm- und Vibrations-Arbeitsschutzverordnung), the risks also need to be assessed reliably at workplaces involving the use of ultrasound. Currently available sound level meters are, however, only suited to a certain extent to measuring sound in this frequency range. Consequently, entities such as professional associations cannot fully fulfill their tasks with regard to the risk assessment of exposed workplaces. We have solved this problem. Within the scope of transferring technology in the TransMeT program, PTB is currently developing a sound level measuring system that covers not only the range of audible sound, but also the ultrasonic frequency range. Our partner (and the direct user of the measuring system) is the Institut für Arbeitsschutz (IFA) of the Deutsche Gesetzliche Unfallversicherung (DGUV).

This development must take numerous requirements, such as those laid down by EN 61672, "Sound level meters", into account. The electromagnetic compatibility of the system must be guaranteed to ensure that the measurement is not biased by strong electromagnetic fields as are encountered at some industrial sites. Moreover, the measuring range should be selected in such a way that the very high sound level pressures occurring locally at workplaces that are exposed to ultrasound can be detected. Due to the short wavelengths of ultrasound, even the smallest of obstacles can hinder its propagation. This must be taken into account when using microphone protection devices or fixtures to cause as little disturbance as possible to the sound field to be measured.

The first prototype of the measuring system has been developed. It can be transported in a case and can be powered by using rechargeable batteries. Tests are currently being carried out to find out whether the system can live up to the special requirements in practical application. A calibration procedure and a measurement method will then be provided.

In the short term, engineers working in occupational health and safety will be provided with a concrete tool to determine and assess the exposure due to airborne ultrasound at workplaces in accordance with the requirements of the relevant standards. In the long run, the findings obtained from this development can be used in standardization and for the development and future commercialization of improved systems.


Moritz Wächtler
Department 1.6
Phone: +49 531 592-8016
E-mail: moritz.waechtler(at)ptb.de

Standards and regulations

Verordnung zum Schutz der Beschäftigten vor Gefährdungen durch Lärm und Vibrationen (German Occupational Health and Safety Regulation on Noise and Vibrations – LärmVibrationsArb- SchV)

EN 61672-1:2013: Electroacoustics – Sound level meters – Part 1: Specifications