I hear you on that question Brian.
For those experimenting with these 2 sound meter apps, the link to the Android app that I have been using for the past couple of months is:
https://play.google.com/store/apps/details?id=com.splendapps.decibel&hl=en_US&gl...=US
All I can add is that it seems consistent over time. When listening to music in my room, I will adjust the loudness level to a subjective "there, that's good" level. Using the app in this post, I am around the same level of 75 - 80 dB consistently. Over 80 is too loud for me.
Last night, experimenting with this one and Brian's (link above) the results were similar - within 2 or 3 dB of each other for a mean over 30 seconds or so. Still, are these readings accurate or off by a certain amount?
My first attempt at finding something more on calibration came up lean, a few users commented on comparing one's sound meter to a known standard and then adding/subtracting to the meter's level which seems inadequate.
Anyone know of a sound meter, probably not an app, that is a "known industrial standard?"