Noise and Noise Pollution FAQ
Learn the answers to common questions about noise and noise pollution. FAQ about noise.
This Noise and Noise Pollution FAQ lists some Frequently Asked Questions about noise.
What is noise?
Noise is defined as unwanted sound. A sound might be unwanted because it is loud, distracting, or annoying.
What is noise?
How is noise measured?
Literally speaking, noise can't be measured directly, since there is no instrument for objectively detecting how "unwanted" something is. What can be measured is the sound level, a quantification of a sound's pressure or intensity and related to its loudness. Sound level is measured in decibels (dB), by a device called a sound level meter.
What is a decibel?
What are typical decibel levels of some common sounds?
A whisper is 30 dB, conversational speech is 60 dB, and someone shouting at you from an arm's length away is 85 dB. Noise levels of home appliances range from 50 dB (a refrigerator) to 95 dB (a food processor). Lawn equipment and power tools have noise levels of 80–120 dB.
Decibel comparison chart
How many decibels can the human ear handle?
Immediate and irreversible nerve damage can be caused by sounds at 140 dB or higher (120 dB in young children). However, damage also occurs at lower sound levels, and this harm accumulates over time. Any sound above 85 dB can cause
wear and tear on your ears
that reduces your hearing acuity over time.
Safe noise exposure limits
What is the loudest sound possible?
Sound is normally carried in air as a pressure wave. When the pressure of a sound wave becomes as high as the air pressure itself, the sound becomes a shock wave. Normal air pressure at sea level is 14.7 pounds per square inch (psi), or 101,325 pascals (Pa), which is equivalent to 194 decibels (dB). So 194 dB is the loudest sound possible in air at sea level; beyond that point it becomes a shock wave. (Sound waves that are transmitted through water or other substances would have different limits.)
What are the effects of noise on human health?
Noise has direct physiological effects such as hearing damage (including hearing loss and tinnitus, or ringing in the ears), as well as cardiovascular and hormonal disturbances. Indirect effects include
interference with concentration and learning, mood changes and aggression, and social isolation.
How noise affects you
How does noise affect babies and children?
Because the ear canal of a young child is smaller than an adult's, sound pressure is up to 20 dB greater than that in an adult ear. In addition to the threat to a child's hearing, noise causes physiological and mental stress, and significantly impacts learning and cognitive development. Background noise also interferes with speech perception and language acquisition.
Hearing protection and children
What is "white noise"?
White noise is a sound similar to radio static, or the sound a fan makes, that is often used to mask unpleasant sounds. Some people find it helpful for sleeping, and it can be a soothing sound for babies.
What is white noise?
Noise Pollution FAQ
What is noise pollution?
Noise pollution is manmade sound in the environment that may be harmful to humans or animals.
What is noise pollution?
What are the most common sources of noise pollution?
Worldwide, the most common sources of noise pollution are cars, trucks, and other motor vehicles. Planes and trains also contribute to noise pollution. Other sources include factory machinery, power tools, and construction equipment.
Examples of noise
What problems does noise pollution cause for people?
World Health Organization (WHO)
cites seven categories for the ways noise adversely affects human health:
How noise affects you
Noise-induced hearing impairment
- Interference with speech communication
- Cardiovascular and physiological effects
- Mental health effects
- Effects on performance of tasks
- Annoyance and effects on behavior
What problems does noise pollution cause for animals?
Wild animals rely on their hearing for detecting predators, finding mates, establishing territory, and recognizing warning alerts. Unnaturally high levels of noise can damage their hearing and can also mask more subtle sounds that they need to hear in order to survive and reproduce. They may also react with a fight-or-flight response to artificial sounds such as aircraft noise, thereby using up valuable energy reserves to flee from a non-existent predator. If noise in an area becomes too intrusive, animals may shift to a new territory or alter their migration patterns, which can create new complications for their mating and survival.
What are the laws regarding noise pollution?
Occupational noise is treated as a health and safety issue and is regulated at the state or national level in many countries. Community noise is typically regarded as a nuisance issue rather than a matter of health, and is normally regulated at local levels of government. The regulations and levels of enforcement vary widely across different communities, and worldwide. Noise-generating products such as automobiles and aircraft may be controlled by industry regulations, and building codes may set requirements for reducing sound transmission in new building construction projects.
Noise pollution laws
What can I do personally to reduce my own noise pollution?
Reducing everyday noise
- Mow your lawn at times that are reasonable for your neighborhood. Avoid using high-noise yard tools such as leaf blowers and power hedge trimmers.
- Keep your motor vehicle's muffler in good condition.
- Only honk your horn in an emergency.
- Train your dog not to bark inappropriately.
- Put your cell phone on "vibrate" mode, and excuse yourself to a private area to conduct a phone conversation.
- Turn off the TV if no one is watching it.
- If you want to enjoy loud music, use headphones.
How can I join with others to reduce noise pollution?
If you have a concern about a specific noise issue in your community, the most effective way to make a difference is to join a local group that shares your concern. If there is no existing group, you may want to organize one yourself.
is a broad-based coalition that can provide you with information, contacts, and tools to help.
Practical Noise Questions
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