Noise emission data for machines and equipment, such as the emission sound pressure level or the sound power level, are a prerequisite for the successful application of the buy-quiet concept, which is intended to protect employees from risk resulting from noise exposure in accordance with the minimization requirement in occupational health and safety. According to the Machinery Directive, the A-weighted emission sound pressure level at the workstation must be declared in the instructions, if it exceeds 70 dB(A). Due to this requirement, this quantity must be determined for most machines. For the determination of emission quantities such as the emission sound pressure level or the sound power level, a hemi-anechoic chamber would be the ideal acoustic environment.
However, acoustic test rooms are not available at most machine manufacturers. Alternatively, emission quantities can be determined by means of in-situ measurements, i.e. measurements in non-ideal acoustic environments, where the measured sound pressure levels are usually influenced by reflections in the room and by background noise. With regard to these influences, in-situ measurement methods correct as far as possible by correction terms.
In this project, the method for determining the local environmental correction according to DIN EN ISO 11202:2010 and its current amendment DIN EN ISO:2010/A1:2020 was investigated with regard to its accuracy and practicability by measurements on a model machine. The positive effects of the amendment - an extended scope and an improved accuracy - were confirmed and errors in a new model for the measurement uncertainty were identified and corrected. In addition, further possible improvements - especially in the determination of the equivalent absorption area of the room - have been pointed out. This quantity is required for the calculation of the local environmental correction and could be determined more precisely and better reproducibly using the method developed in project F 2438. The method from project F 2438 and the knowledge gained here can be used to further improve the practicality and accuracy of this measurement method in a future revision of DIN EN ISO 11202.
Unit 2.2 "Physical Agents"
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