Near Field Acoustic Camera
Sound source localization is an important topic in the working field of sound & vibration, from the product development stage to the end off line control of products. The Microflown PU-based Near Field Acoustic Camera is a very fast and accurate system for sound source localization. The sound pressure can be seen as a result of an object making too much noise where the particle velocity is very well suited to localize the cause of why an object is making too much noise. The Near Field Acoustic Camera can be used in real operating conditions and in reverberant conditions, it is no longer needed to have or create anechoic conditions. Unlike traditional techniques the array of sensors is not consisting only of sound pressure microphones but of PU sound intensity probes. The Near Field Acoustic Camera measures the particle velocity directly, which means that there are no complex and inaccurate computation steps. Hence, the Microflown Acoustic Camera yields an accurate particle velocity map in the full audible frequency range. Due to the fact that no reconstructions are required easily a dynamic range of +40dB can reached and visualized. The dynamic range is frequency independent so for all frequencies the same high dynamic range can be reached. The method displays absolute values for the sound pressure, particle velocity and sound intensity. Since the Near Field Acoustic Camera directly visualizes measurement data in the frequency domain, the spatial resolution is just the sensor spacing, which is typically only a few centimeters, and it can be changed easily. An area can be covered with a coarse grid first. Later the sensor spacing can be decreased to cover a smaller area with a very high resolution, like a zoom function on a normal camera. Especially in the low frequency range, the resolution that can be achieved this way is unparalleled by any microphone-based method. The results can be visualized as a function of time as the phase information is maintained in this full-array measurements. This means that non-stationary problems such as engine run-ups can be evaluated reliably in an unparalleled frequency range and by looking in the time domain transient noises like squeak & rattles can easily being detected for all frequencies. The Near Field Acoustic Camera introduces a fast, accurate and intuitive solution for this daily issue. Cars, aircraft, consumer goods all can be tested nowadays with Near Field Acoustic Camera.
- Chapter 8: Near field acoustics (PDF)
- Standard probes
- Sources | VVS
- Velo Software