You can measure the environmental noise in decibels. Sound Level Meter is the part 4. of Smart Tools series. (noise) Acoustimeter uses your phone mic to measure noise volumn in decibels(dB) and shows a reference. SPL(sound pressure level) noisemeter.
Decibel X is one of very few noise meter apps with highly reliable, pre-calibrated measurements and supports dB468, dBA, dBC. It turns your mobile device into a professional sound level meter, precisely measures the sound pressure level (SPL) all around you.