The only value you can get from Microphone is activityLevel. You can't get the rough dB value of your sound source from multiple reasons:
Your soundcard may oper a dynamic amplification/compression of the sound, which means a quiet sound may have the same level of a loud one on the output.
The response of your microphone is not linear, you must know precisely the curve of its response to get the real volume of your source.
Your material is not calibrated, you will get a relative value. You would need a certified sound source to match the value you get to the real amount of dB.
The only value you can get from Microphone is
activityLevel
. You can't get the rough dB value of your sound source from multiple reasons:Sorry, cheers!