Thanks to all :-) very helpful

Trying out "Sound Meter" by Smart Tools co., they mention Galaxy Tab, which I use, so that should be good. The db meter seems stable, where another app I tried was swinging from 20db to 60db constantly.

I looked up a few of these for my Android, and found out that according to a few developers, they are limited to a max level by the microphone in these devices.
 
But for your purposes, this may get the job done for monitoring at 80-85dB.
 
For example: Mobile Essentials https://play.google.com/store/apps/details?id=com.soundmeter.app&hl=en
"Microphones in Android devices are made to record human voice, therefore the maximum noise is limited and very loud sounds cannot be recognized (in most cases above 100dB)".
 
Smart Tools co. https://play.google.com/store/apps/details?id=kr.sira.sound&hl=en
I calibrated major android devices with an actual meter. You can trust the result in routine-noise levels (40-70dB).
 
Abc Apps https://play.google.com/store/apps/details?id=com.gamebasic.decibel&hl=en
Microphones in most android devices are aligned to human voice. The maximum values are limited by the device. Very loud sounds(over ~90 dB) may not be recognized in most device.
 
Fascinating!

NIH Links discussed above:
link1
link2
 
Interesting they claim the iPhone 3 is the most accurate. It's microphones have the looser tolerance than the iPhone 5.
 
SoundMeter seems to be the best and NoiSee and Noise Hunter are the next best. Those are within 2dB of their standard.

fret_man
NIH Links discussed above:
link1
link2
 
Interesting they claim the iPhone 3 is the most accurate. It's microphones have the looser tolerance than the iPhone 5.
 
SoundMeter seems to be the best and NoiSee and Noise Hunter are the next best. Those are within 2dB of their standard.

Interesting ...
 
More than 130 iOS apps were evaluated but only 10 apps met our selection criteria. Only 4 out of 62 Android apps were tested.
 
A total of 62 Android apps were examined and downloaded from the Google Play store but only 4 apps (SPL Meter by AudioControl, deciBel Pro by BSB Mobile Solutions, dB Sound Meter by Darren Gates, and Noise Meter by JINASYS) partially met our selection criteria*.
 
*Smartphone apps were selected based on occupational relevancy criteria: (1) Ability to report unweighted (C/Z/flat) or A-weighted sound levels, (2) 3-dB or 5-dB exchange rate, (3) slow or fast response, and (4) equivalent continuous average sound level (Leq) or time-weighted average (TWA). Also, considerations were given to apps that allow calibration adjustment of the built-in microphone through manual input or digital upload files as well as those with reporting and sharing features. For the purpose of this experiment, the apps were not calibrated to the reference sound level and were tested with their original calibration settings to simulate a typical user experience that may not have access to a calibrated sound source or equipment.

Some phones have built in auto gain reduction on the Mike that throws of the measure.

Spl meters are so cheap that I'm sure you could afford one with the proper weighting ... not everything needs to be smartphone apps ;-)

Rob[atSound-Rehab]
Spl meters are so cheap that I'm sure you could afford one with the proper weighting ... not everything needs to be smartphone apps ;-)

$17.75 w/battery.  Amazon #1 Seller in Sound Measurement
 
BAFX Products® - Decibel Meter / Sound Level Reader - W/ Battery!
https://www.amazon.com/BAFX-Products-Decibel-Reader-Battery/dp/B00ECCZWWI/ref=sr_1_1?ie=UTF8&qid=1485390739&sr=8-1&keywords=spl+meters
 

abacab

Rob[atSound-Rehab]
Spl meters are so cheap that I'm sure you could afford one with the proper weighting ... not everything needs to be smartphone apps ;-)

$17.75 w/battery.  Amazon #1 Seller in Sound Measurement
 
BAFX Products® - Decibel Meter / Sound Level Reader - W/ Battery!
https://www.amazon.com/BAFX-Products-Decibel-Reader-Battery/dp/B00ECCZWWI/ref=sr_1_1?ie=UTF8&qid=1485390739&sr=8-1&keywords=spl+meters
 

Well that's cheap...but still the app is free and seem to have a good rep, so I think I'll stick to that for now :-)

While getting the spl level in the ballpark is great, (+-3db) having consistent levels day in and out is also important.