Sound pressure - free-field based sound power
Noise emission quantities from machinery and equipment are increasingly becoming the subject of national and international regulations with the aim of a safer and healthier working place and of environmental protection.
For example, all household appliances sold in the EU, from vacuum cleaners to refrigerators, must feature an energy label including sound power information. For washing machines, for example, this must cover both wash and spin cycles.
Noise declarations are meant to help buyers to compare noise emissions of machinery on the market and thus to choose comparatively quiet machines. Simultaneously, any company that manufactures certified products fulfilling the EU noise emission requirements has the opportunity to enter a bigger market with fewer import barriers.
One of the three main methods for determining the noise emission of products is through free-field based sound power, where the source is placed in an acoustically open area (free field) and its sound power determined from sound pressure measurements.
Depending on need, two complete turnkey systems are available that enable you to determine sound power in essentially free-field environments and that simplify the measurement procedure right up to the final report. For infrequent or variable testing needs, a sound level meter-based product noise application is a good fit for measuring sound power levels according to ISO 3744 and ISO 3746 and EU Directive 2009/125/EC.
For more frequent measurements under static conditions, the PULSE- and LAN-XI-based system adds additional microphone and tachometer probe possibilities along with compliance with a wider range of ECMA and ISO standards and test codes. A reference sound-source for determining environmental correction can be used with either system.