Brian Barton
Noise pollution is any unpleasant, damaging, or irritating noise that has the potential to harm people, wildlife, or the environment. It is commonly generated in many industrial facilities and some other workplaces, but it can also come from highway, railway, and airplane traffic, as well as outdoor construction activities. The unit used to measure noise pollution is the decibel (dB). The louder the noise, the higher the decibels. The normal human ear can detect sounds ranging between 0 dB (hearing threshold) and about 140 dB, with sounds between 120 dB and 140 dB causing pain.
| Characteristics | Values |
|---|---|
| Unit of Measurement | Decibels (dB) |
| Noise Level | The louder the noise, the higher the decibels |
| Adjusted Scale | Decibels can be adjusted to human hearing, and are described in decibels A (dBA) |
| Prolonged Exposure | Exposure to 75 dBA over eight hours a day for years can lead to hearing loss |
| Sleep Disturbance | Outdoor noise of 40 dBA can disturb sleep |
| Hearing Loss | Noise above 120 dB causes pain and can lead to hearing loss |
| Health Hazards | Extreme noise exposure can increase blood pressure and pulse rates, cause anxiety, and mental fatigue |
| Noise Sources | Industrial facilities, highway, railway, and airplane traffic, outdoor construction activities |
| Noise Protection | Noise-cancelling headphones, noise insulation windows and doors |
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What You'll Learn
- Decibels (dB) are the main unit of measurement for noise pollution
- Noise above 65 dB is defined as noise pollution by the World Health Organization (WHO)
- An increase of 10 dB represents a 10-fold increase in sound intensity
- Loudness, or sound pressure level (SPL), is calculated in decibels
- Equivalent sound levels (Leq) can be used to express an average SPL over a given period
Decibels (dB) are the main unit of measurement for noise pollution
Noise pollution is defined as any unnecessary, unpleasant, or excessive sound that can have harmful effects on human health, wildlife, and the environment. It is often created in industrial facilities and some other workplaces, as well as by highway, railway, and airplane traffic, and outdoor construction activities.
The loudness of a sound, also known as sound pressure level (SPL), is measured in decibels. The normal human ear can detect sounds ranging from 0 dB (the hearing threshold) to approximately 140 dB, with sounds between 120 dB and 140 dB causing pain. According to the World Health Organization (WHO), noise becomes harmful when it exceeds 75 dB, and noise pollution is defined as noise above 65 dB.
To provide some context, a construction drill may cause a noise level of about 90 dB. If two identical drills operate side by side, the noise level increases to 93 dB. When two sounds with a difference of more than 15 dB in SPL are combined, the weaker sound is masked by the louder one. For example, an 80 dB drill operating next to a 95 dB dozer will result in a combined SPL of 95 dB, with the less intense sound of the drill being drowned out.
It is important to note that noise levels vary with time, so noise measurement data are often reported as time-averaged values to express overall noise levels. For instance, L90 = 75 dBA indicates that the noise levels were equal to or higher than 75 dBA for 90% of the time. Equivalent sound levels (Leq) can also be used to express an average SPL over a specific period, such as an eight-hour workday.
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Noise above 65 dB is defined as noise pollution by the World Health Organization (WHO)
The unit of measurement for noise is the decibel (dB). This unit measures the loudness or sound pressure level (SPL) of noise.
Noise pollution is defined by the World Health Organization (WHO) as noise that exceeds 65 decibels (dB). According to the WHO, noise becomes harmful when it surpasses 75 dB, and it is painful when it exceeds 120 dB. The organization recommends that noise levels remain below 65 dB during the daytime and below 30 dB at night to ensure restful sleep.
Noise pollution is any unwanted or excessive sound that can have detrimental effects on human health and ecological quality. It is typically generated in industrial facilities and other workplaces, as well as from sources such as highway, railway, and airplane traffic, and outdoor construction activities.
The impact of noise pollution on human health is significant. Prolonged exposure to loud noises, such as 75 dB over eight hours a day for years, can lead to hearing loss. Additionally, noise pollution can disturb sleep, even at lower levels of 40 dB. It can also cause irritability, anxiety, and mental fatigue, and can affect people's ability to focus and memorise information.
Noise pollution also has negative effects on children and adults on the autistic spectrum. Those with Autism Spectrum Disorder (ASD) may experience hyperacusis, an abnormal sensitivity to sound, which can lead to unpleasant emotions, fear, and physical discomfort in noisy environments. This can result in isolation and a decreased quality of life.
The WHO has recognized the harmful effects of noise pollution and has released guidelines to regulate community noise, providing recommendations for limits and preventive measures for various noise sources, including road traffic, railway, and aircraft noise. These guidelines aim to protect public health and well-being by reducing the impact of noise pollution.
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An increase of 10 dB represents a 10-fold increase in sound intensity
The unit used to measure noise pollution is the decibel (dB). Decibels are logarithmic units used to calculate sound intensity and loudness (also called sound pressure level or SPL). An increase of 10 dB is perceived as a doubling of sound volume, but it actually represents a 10-fold increase in sound intensity.
Sound intensity is the energy (power) needed to produce a given level of sound. It is calculated using the following formula: x-fold increase in sound intensity = 10^(ending dB value – starting dB value)/10. For example, to find the increase in sound intensity between 10 dB and 15 dB, you subtract 10 from 15, which gives you an exponent of 0.5. Raising 10 to the power of 0.5 yields 3.162, meaning the intensity increase between 10 dB and 15 dB is 3.162-fold.
It is important to distinguish between sound intensity and sound volume. While sound intensity refers to the amount of energy required to produce a given level of sound, sound volume refers to the level at which we perceive the resulting sound. Our ears perceive sound logarithmically, so a sound of 120 dB is perceived as about 4,000 times louder than a sound of 0 dB, rather than 1 trillion times louder as a linear scale would suggest.
Noise pollution refers to unnecessary or extreme sounds that can have harmful effects on human health and ecological quality. It is typically created in industrial facilities, workplaces, and from traffic and outdoor building activities. Prolonged exposure to loud noises, such as 75 dBA over eight hours a day for years, can lead to hearing loss. Additionally, exposure to noise levels above 85 dBA for eight hours can result in temporary or permanent hearing loss.
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Loudness, or sound pressure level (SPL), is calculated in decibels
The loudness of noise pollution, or sound pressure level (SPL), is calculated in decibels (dB). Decibels are logarithmic units, meaning that a 10 dB increase represents a tenfold increase in sound intensity, while a 20 dB increase represents a 100-fold increase in sound intensity. The normal human ear can detect sounds ranging from 0 dB (hearing threshold) to 140 dB, with sounds measuring 120 dB or above causing pain.
The World Health Organization (WHO) defines noise above 65 dB as noise pollution, with noise exceeding 75 dB considered harmful. Nighttime ambient noise levels above 30 dB can disrupt sleep. Prolonged exposure to loud noises of 75 dB over eight hours a day for years can lead to hearing loss. Sources of noise pollution, such as industrial facilities, workplaces, highway traffic, and construction activities, often produce sounds exceeding 85 dB, which is considered harmful.
To address noise pollution, environmental and noise control engineers work on designing and testing noise insulation technologies and sound-absorbent materials. They aim to develop new technologies that produce less noise and meet recommended standards. Examples of noise protection products include noise-cancelling headphones, noise insulation windows, and doors.
Noise level measurements are reported as time-averaged values to account for variations over time. For instance, L90 = 75 dBA indicates that the noise levels were at or above 75 dB for 90% of the time. Equivalent sound levels (Leq) are used to express the average SPL over specific periods, such as an eight-hour workday. Leq is a logarithmic average that gives more weight to louder events.
Additionally, day-night sound levels (DNL or Ldn) consider the increased sensitivity to noise during nighttime. A 10-dBA penalty is added to SPL values measured between 10 pm and 7 am, making DNL measurements particularly useful for assessing community exposure to aircraft noise.
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Equivalent sound levels (Leq) can be used to express an average SPL over a given period
The unit of measurement of noise pollution is the decibel (dB). Decibels can be adjusted to human hearing and are described in decibels A (dBA). Prolonged exposure to loud noises of 75 dBA over eight hours a day for years can lead to hearing loss.
Sound pressure level (SPL) is a ratio of sound pressure and reference sound pressure, expressed in decibels (dB). SPL is a logarithmic scale that measures the pressure level of a sound wave relative to a reference level. It is typically measured using a sound pressure level meter (SLM) which includes a microphone, processing section, and display. The SLM converts sound pressure waves into electrical signals, then into digital signals so they can be displayed in the form of decibels.
Equivalent continuous sound level (Leq) is a common way of measuring SPL over a period of time. It is a time-averaged measure of sound pressure levels over a specified period, typically frequency-weighted, but without the Fast or Slow time-weighting used in SPL measurements. Leq is a linear measure that does not incorporate time weightings.
Leq is calculated using sound pressure and time duration, accounting for frequency weighting. It represents the average sound level over a designated period, treating fluctuating sound levels as equivalent energy to a constant sound level. Leq is widely used but not widely understood. It is based on an exchange rate of 3 dB and can be measured over any suitable time, called integration time.
Leq results hold the same energy content and potential hearing damage as varying sound levels. Leq is a crucial metric in acoustics and noise studies, providing information on how much energy a person was exposed to. It is used for many types of acoustic measurements, including building acoustics, environmental noise, and occupational noise.
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Frequently asked questions
The unit of measurement of noise pollution is the decibel (dB).
The decibel scale is logarithmic, meaning that an increase of 10 dB represents a 10-fold increase in sound intensity, an increase of 20 dB represents a 100-fold increase, and so on.
Noise pollution can lead to physical injury to the eardrum and the receptive hair cells of the inner ear, resulting in temporary or permanent hearing loss. It can also cause increased blood pressure and pulse rates, irritability, anxiety, and mental fatigue.
