The formula of deecibel calibration

[Jens Noriʇzsɔɥ]

The audio signal is not normalised so phyphox cannot relate it to any physics quantities. The SPL (in dB) is log based so any proportionality factor becomes a summand, however, still unknown. If you have a reference signal with a known SPL, you can enter it in the “Calibration” tab and tap “Calibrate“. This automagically computes an offset. Please note that the SPL depends on the distance to the sound source.

There is quite some intricacy to the calibration process. You could find some (further) notes on this in the “FAQ” tab and at our wiki, https://phyphox.org/wiki/index.php/Exper..._Amplitude, that is linked from the three-vertical-dots menu.