(in German)

According to the NOMAD study (2012) 80 % of the noise emission declarations of machines, demanded by European directives, were not reliable. Possible causes are, among other things, the high costs and the complexity of the normative measuring methods for the noise emission characteristics. For small and medium-sized enterprises (SMEs), self-performed measurements in their own premises would be a cost-effective alternative. These partly fail due to the necessary determination of the environmental correction of the room in which these measurements are to be carried out. Within the framework of the project outlined, a simple method for determining the environmental correction, which is practicable for SMEs, is to be developed.

A possible method for qualifying the measurement environment works with the help of a reference sound source (RSS). The idea of the project is to replace this expensive RSS with a small, portable machine (e.g. industrial vacuum cleaner, air compressor), available in every company, and to determine its sound power according to a noise test code in the acoustic free field, approximated by a free, sound-reflecting surface outside at low background noise. Subsequently, this substitute RSS is brought into the room, in which the newly manufactured machines will be measured, and its sound power is measured there again. Since the sound power level determined there is higher because of sound reflections in the room, the environmental correction for this room and the measurement surface used is obtained from the difference between the two sound power levels. However, certain requirements for the substitute RSS must be met and the limits of the accuracy of the method must be observed.

Please download the complete report "Noise emission from machines - Simple approximate determination of the environmental correction" (in German only).