Introduction

Microflowns can be calibrated in several ways. Two methods are standard nowadays: The  small standing wave tube Can be used in a 20Hz-3.5kHz bandwidth and is simple to use: one needs to use one equation to obtain the calibration data. The method is not affected by background noise.   The piston on a sphere calibration technique It is a free field method that requires some space. The method works in the full acoustic bandwidth. The method requires some software to operate.