REMEMBER!! The built-in microphones were aligned to human voice (300-3400Hz, 40-60dB). Therefore the maximum values are LIMITED by the hardware limitation, and very loud sound(100+ db) cannot be recognized. Moto Droid (max.100), Galaxy S3 (81dB), Galaxy Note (91dB), Galaxy S2 (98dB)...

SPL(sound pressure level) meter app uses your built-in microphone to measure noise volume in decibels(db), and shows a reference. We had calibrated many android devices with the actual sound level meter with dB(A).

See the 4-6th pictures. I had calibrated many android devices with an actual sound level meter. You can trust the result in routine-noise levels (40-70dB). But, please use it as an auxiliary tool.

* Pro version added Features :- Sound Meter and Vibrometer are integrated- Statistic menu with saving log data- CSV file exporting- Level notification- Line-chart duration- More models are calibrated- No ads

* Do you want more tools?Get [Sound Meter Pro] and [Smart Tools] package.

For more information, see the manual, Youtube video and the blog. Thank you.

** Not compatible with: Xperia(X8, X10 mini), LG(Optimus One, P350), GT-I9001, ZTE, etc