The Federal Institute for Occupational Safety and Health (BAuA) is fostering the purchase of quiet machines "Buy Quiet" as an important measure for noise reduction at workplaces. An essential prerequisite are appropriate noise emission declarations provided by the machine manufacturer. However, the European market surveillance activity "NOMAD" has shown that only 20% of all noise emission declarations are actually reliable. An important reason for this is the complexity of existing noise emission measurement standards. DIN EN ISO 3744 is the most commonly used standard for determining the sound power level. It allows carrying out the required measurements under in situ conditions by correcting measurement results for influences of background noise and room reflections. Without sufficiently specifying the scope of application, the standard presents several methods for determining the environmental correction. Within intensive investigations on DIN EN ISO 3744 the BAuA systematically investigated the different methods dealing with the determination of the environmental correction. A model machine was applied in order to carry out measurements in different industrial-type environments. The results show a good estimation of the room influences, especially for the favoured absolute comparison test. At the same time problems were identified when applying specific methods under special environmental conditions. Among other things the influence of the measurement environment on the emitted sound power of sound sources will be discussed.
Please download the article "Methods for defining the environmental correction according to DIN EN ISO 3744 when determining the sound power level of machines in industrial environments" (in German only).
I. Arendt, P. Kurtz:
Verfahren zur Ermittlung der Umgebungskorrektur nach DIN EN ISO 3744 bei Ermittlung des Schallleistungspegels von Maschinen in industriellen Umgebungen.
in: Lärmbekämpfung 3/2017 2017. pages 86-91, PDF file