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Into the Future with Metrology - The Challenges of Medical Technology

Ultrasound noise measured directly on the person – a device developed by PTB can contribute to more accurate assessment of the airborne ultrasound exposure

30.05.2022

A high-frequency personal sound exposure meter (High-Frequency and Ultrasound Personal Exposimeter - HiFUSPEx) newly developed in department 1.6 possesses the measuring capabilities of a “real” sound level meter, but as a fully portable device it can record person’s individual ultrasonic noise exposure.

For years, airborne ultrasound exposure has been associated, especially at industrial workplaces, with negative health effects. Until now, there has been a lack of suitable technology and methodology to measure ultrasound exposure in a reliable manner. Due to their complexity, ultrasonic fields cannot be captured with classic hand-held sound level meters, because these are intended for stationary measurements in the absence of an employee. In such cases, when the hand-held sound level meters are not suitable, individual measurements are carried out with sound exposure meters. However, until now these devices have only been designed for the medium audio frequency range up to 8 kHz.

Therefore, a high-frequency personal sound exposure meter (Figure 1) was developed in cooperation between the PTB and the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA of the DGUV) as part of a technology transfer. It is primarily intended for person-oriented measurements because the ultrasound exposure is directly linked with an individual impact of the ultrasonic noise on a person. Nonetheless, the device can also be applied as a hand-held sound level meter in the audible frequency range.

 

Figure 1. Functional model of the HiFUSPEx. The device can be attached to the belt, for example, while the remote microphone with integrated accelerometer is positioned in front of the ear using a head or shoulder mount.

 

For a person-oriented measurement the microphone, which is comparatively small and freely positioned, can be attached close to the ear of the person concerned (Figure 2). Due to the small wavelengths of the airborne ultrasound, the distance to the ear must be kept as short as possible so that the sound pressure reaching the ear can be realistically determined. The device itself is attached to the person’s body, for instance to a belt, and thus can be carried irrespective of a person’s location.

 

 

Figure 2: Exemplary use of the HiFUSPEx with shoulder mount (left, with two synchronized devices used on both ears) and with a single device and a head mount (right).

 

The device developed was validated by comparative analysis with an ultrasound measurement system (USPM), which was previously tested up to 100 kHz [2]. In a series of measurements in various simulated industrial work scenarios, both devices have provided comparable results [3]. The spatially resolved measurement data on ultrasonic fields collected in this way are also of interest for other applications and analyses and as such will be published in a database [4]. 

Practical tests are currently being carried out with the existing version of the device (Figures 1 and 2). At the same time, measurement and calibration procedures for routine usage are being developed. The functional model is now expected to be transformed to a practical prototype ([1], technology offer 7095).

 

Literature:

[1] Physikalisch-Technische Bundesanstalt, PTB Innovationen Technologieangebot “Ultraschallexposimeter für den praktischen Arbeitsschutz,” 2021. [Online]. Opens external link in new windowLink

[2] M. Wächtler, M. Rust, A. Wolff, and C. Kling, “Development of an ultrasound level meter for use in occupational safety and health,” J. Acoust. Soc. Am., vol. 149, no. 4, pp. 2836–2847, 2021, Opens external link in new windowdoi: 10.1121/10.0004787.

[3] M. Cieslak, C. Kling, and A. Wolff, “Development of a Personal Ultrasound Exposimeter for Occupational Health Monitoring,” Int. J. Environ. Res. Public Health, vol. 18, no. 24, 2021, Opens external link in new windowdoi: 10.3390/ijerph182413289.

[4] M. Cieslak, C. Kling, and A. Wolff, "Dataset of the high-frequency and ultrasound personal exposimeter (HiFUSPEx) validation scans performed in three simulated industrial sound fields", 2022, PTB Open Access Repository; Opens external link in new windowdoi:10.7795/720.20211214. (dataset not published, yet)

 

Contact:

Michal Cieslak, FB 1.6, email: Opens local program for sending emailmichal.cieslak(at)ptb.de