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

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

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