Microflown Technologies - Piston on a Sphere

Piston on a Sphere Calibrator

The "piston on a sphere calibration method" is based on a loudspeaker build in a sphere.
The impedance of the source is known and that is the basis of this calibration method for higher frequencies (f>100Hz).

For lower frequencies the reference pressure microphone is put in the sphere.
In such way the velocity of the loudspeaker can be determined.
Once the velocity of the loudspeaker is known, the velocity in front of the speaker is determined.
This method works from 20Hz up to 200Hz.

A PU probe can be calibrated in the full acoustic bandwidth with two measurements.

The method is proven to be very accurate.

Datasheets and Manuals

More Info

Background information can be found in Chapter 4: 'Calibration' and Chapter 4A: 'Standard calibration techniques'
Scientific papers on the subject of Calibration
Presentation on calibration can be found at the presentations page
Video presentation of the 'Piston on a Sphere Calibration' can be found at the video page

Key Papers

A note on the calibration of pressure-velocity sound intensity probes,
Finn Jacobsen et al, JASA 2005.

High Frequencies

Low frequencies