dBA Meter app well calibrated with professional noise meter tool OKTAVA 110A-PRO.

Measure sound level/noise:
-Current average level
-Peak level
-Average maximum level
-Absolute maximum level

Graph histogram for (change in settings):
-Current average level
-Peak level

Additional features:
-Save measurements
-Upside down orientation to easy use.


To reset maximum or average maximum - just tap on it.
You can self calibrate it in settings (range from -20.0dB to +20.0dB)