A laboratory study for occupational safety and health on the structure of airborne ultrasound fields

Robert Schöneweiß,Christoph Kling,Christian Koch

doi:10.1051/aacus/2020013

Robert Schöneweiß, Christoph Kling + Show 1 more

Open Access

https://doi.org/10.1051/aacus/2020013

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Abstract

While exposure to airborne ultrasound is increasing in occupational contexts and in public and private spaces, existing demand for reliable and traceable determination of exposure to sound with frequencies above 16 kHz cannot currently be satisfied due to a lack of adequate measurement devices and procedures adapted to the specifics of airborne ultrasound. So that this study may serve as a first step for the development of a novel measurement procedure, its aim is to create a comprehensive database of the structures of airborne ultrasound fields present in occupational contexts. Based on this, the limitations of measurement procedures commonly used in the audible frequency range are clarified and the structural characteristics of airborne ultrasound fields investigated. This paper presents a laboratory study of the structure of the airborne ultrasound field of an ultrasonic welding machine, which can be considered a representative occupational source of airborne ultrasound. For this study, the technical and procedural requirements of a measuring system are derived and used to set up and calibrate a measuring system for three-dimensional, high spatial resolution scans of sound pressure levels in the laboratory. The measurement results reveal complex, extensive and very fine-structured interference patterns, some of which have sound pressure levels of up to 138 dB (re 20 μPa).

Highlights

While exposure to airborne ultrasound is increasing in occupational contexts and in public and private spaces, existing demand for reliable and traceable determination of exposure to sound with frequencies above 16 kHz cannot currently be satisfied due to a lack of adequate measurement devices and procedures adapted to the specifics of airborne ultrasound
That this study may serve as a first step for the development of a novel measurement procedure, its aim is to create a comprehensive database of the structures of airborne ultrasound fields present in occupational contexts
Manufacturer data and measurement procedures based on quantities and definitions that were created for the audible frequency range did not always allow conclusions to be drawn for the ultrasonic frequency range

Summary

Introduction

Exposure to airborne ultrasound is increasing in occupational contexts and in public and private spaces [1]. Sources of airborne ultrasound can be found in areas as diverse as laboratory and medical technology, measurement devices, and industrial applications such as cutting, welding, and cleaning. Research on how humans perceive airborne ultrasound or are otherwise impacted by it, as well as on the development of measurement devices and procedures, has not matched the pace at which ultrasound technology has proliferated. The validation of measurement devices and measurement procedures is limited to the audible frequency range, with regard to occupational safety and health. It is at best questionable whether a simple application of measurement procedures commonly used in the audible frequency range to ultrasonic frequencies is effective.

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