SoundMeter

Sound Meter is professional sound meter for your Android. Sound Meter is also known as sound level meter, decibel meter (dB meter), noise meter, sound pressure level meter (SPL meter). Sound Meter uses your Android's microphone to measure levels of noise or sound pressure levels and displays measured data in dB (decibels) with reference to generally known noise (provided by American Academy of Audiology) or displays the noise data on easy to read graph for the last 30 seconds of app use.
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). Sound Meter PRO is calibrated to be accurate in +-2.5 dB range of actual noise level and is probably by far the most accurate sound meter on Google play. We have adjusted Sound Meter with the use of professional sound meter used by sound engineers and made required adjustments for many Android devices, including the most popular devices on the market today.
Levels of Noise In decibels (dB) according to American Academy of Audiology (www.audiology.org):
140 dB - Gun shots, fireworks
130 dB - Jackhammers, Ambulance
120 dB - Jet planes taking off
110 dB - Concerts, Car horns
100 dB - Snowmobiles
90 dB - Power tools
80 dB - Alarm clocks
70 dB - Traffic, vacuums
60 dB - Normal conversation
50 dB - Moderate rainfall
40 dB - Quiet library
30 dB - Whisper
20 dB - Leaves rusting
10 dB – Breathing