normal range of human hearing extends from about 0 dB to about 140
dB. The level of 0 dB is the threshold of hearing, which corresponds to sound
pressure level of 20 ÁPa, the minimum detectable sound pressure
level by average human ear. A 10 dB increase
in the level of a continuous noise represents a perceived doubling
of loudness; a 5 dB increase is a readily noticeable change, while a
3 dB increase is barely noticeable to most people.
levels above 85 dB are considered harmful, while 120 dB is unsafe
and 150 dB causes physical damage to the human body. Windows break
at about 163 dB. Jet airplanes cause about 133 dBa at 33 m, or 100
dBa at 170 m distance. Eardrums rupture at 190 dB to 198 dB. Shock
waves and sonic booms cause levels of about 200 dB at 330 m. Sound
levels of around 200 dB can cause death to humans and are generated
near bomb explosions (e.g. 23 kg of TNT detonated 3 m away). The
Space Shuttle generates levels of around 215 dB (or about 175 dBa)
at 17 m.