Manual Calibration

Manual calibration can be done with setting page. You need to press menu to have the setting item:

Note: in some devices, you may press the 3 dots menu item at the right top corner, like: 

There is a calibration menu item in setting page. After touch it, you may find:

miidio Noise Meter starts noise meter and gives you the calibrated result in the real time.

Finally, just press ok to save the calibration.

Note: after you changed calibration value. You need to stop SPL calculation and start it again to take calibration effect.