The microphone measures the environmental sound level in decibel(dB).

171 dB Next to a loud rifle being shot
150 dB Right next to a jet engine
110-140 dB Jet engine at 100 meters
130-140 dB Where most people begin to feel pain
130 dB Trumpet (a half meter in front of)
120 dB Vuvuzela horn (1 meter in front of)
110 dB Gas chainsaw
100 dB Jack hammer
80-90 dB Traffic on a busy roadway
60-80 dB Passenger car
40-60 dB Normal conversation
20-30 dB Very calm room
10 dB Light leaf rustling, calm breathing
0 dB Hearing threshold right next to ear