文档介绍：10、Noise, Killer of Mankind
Unwanted sound, or noise, such as that produced by airplanes, traffic, or industrial machinery, is considered a form of pollution is at its worst in densely populated can cause hearing loss, stress, high blood pressure,sleep loss,distraction,and lost productivity.
Sounds are produced by objects that vibrate1 at a rate that the ear can detect2. This rate is called frequency and is measured in hertz3, or vibrations per second. Most humans can hear sounds between 20 and 20,000 hertz, while dogs can hear high-pitched4 sounds up to 50,000 hertz. While high-frequency sounds tend to be more hazardous5 and more annoying to hearing than low-frequency sounds, most noise pollution damage is related to the intensity of the sound. Measured in decibels6, noise intensity can range from zero, the quietest sound the human ear can detect, to over 160 decibels. Conversation takes place at around 40 decibels, a subway train is about 80 decibels, and a rock concert is from 80 to 100 decibels. The intensity of a nearby jet taking off is about 110 decibels. The threshold for pain, tissue damage, and potential hearing loss in humans is 120 decibels. Long-lasting, high-intensity sounds are the most damaging to hearing and produce the most stress in humans.
Solutions to noise pollution include adding insulation7 and sound-proofing8 to doors, wall