Manufacturing industries

Sound Power

SI2 SoundIntensity2 SI3 Click to enlarge

Sound power is the measurement of the acoustic power radiated by an object. The sound power value is nowadays a important parameter for noise emission of products. It is used in a lot of markets such as in automotive, white goods, ground vehicles and many more.

On method to determine sound power is to use the sound intensity. Any sound field is described by two complementary acoustic properties, the scalar value 'sound pressure' and the vector value 'acoustic particle velocity'. The product of sound pressure and acoustic particle velocity is giving the Sound Intensity. Before particle velocity sensors became available, a finite difference approximation of the pressure gradient using two phase matched pressure transducers (the so called p-p method) estimated the particle velocity signal. The Microflown PU probes directly measure both quantities in one spot. Due to the near field benifits using the direct measurement of the directional particle velocity measurements can be undertaken in real operational situation even in cases with a high pressure over intensity ratio. PU probes are very small and broad banded without any spacing requirements, facilitating the ease of use significantly.

The use of an array of p-u probes  makes it possible to measure the complete product  as for example an car engine in just one single, short measurement. From a technical point of view, a scanning p-p intensity can only be used to measure stationary problems. With an array of p-u probes, multi point measurements evaluating instationary problems  become possible. As the total product is covered and the complete measurement is done in one run, all phase information is kept and accurate results  are achieved  even at lower frequencies. The measurements  can even be conducted in non anechoic conditions. With the sound power emission known for each sub component, allows verifying or improving the acoustic performance of each component. And finally  the information needed to reduce the global noise emission.

Features

  • Frequency range 20Hz - 20kHz
  • Both quantities, sound pressure and particle velocity, directly measured at one point
  • Low suscepebility to background noise and reflections
  • No need for anechoic room or anechoic conditions
  • High spatial resolution
  • Non stationary measurements are applicable