Noise pollution

Loud sounds can be a problem.

Many things make noise. Cars and planes are big sources.

Machines and building work also make noise. This noise can hurt people. It can also hurt animals. Loud noise can make it hard for animals to find food. It can even hurt their hearing.

We use tools to see how loud a sound is. This helps us keep our world a bit quieter.

Noise pollution is sound that can harm people and animals.

Many things make noise in our world. Machines and transport are big sources.

Cars, planes, and trains create much noise. Building work and lawn tools also add to it.

In people, loud noise can cause stress. It can also hurt sleep and heart health. It can even cause hearing loss. For animals, noise is a big problem too. It can make it hard for them to find food or avoid danger. It can also stop them from having babies.

Scientists measure how loud a sound is using decibels (dB). This is a scale for loudness. Road noise is often 70 to 100 dB. Sounds above 85 dB can hurt your hearing. People use a tool called a sound level meter to study this.

These tools have a microphone to catch the sound. Some scientists even use apps on a smartphone to help. These apps can show how loud a sound is in real time.

Noise pollution is sound that can harm people and animals.

It happens when sounds are too loud or unwanted. Many things in our world create this kind of noise. Machines and transportation are the biggest sources of outdoor noise.

In cities, traffic from cars and buses is a major cause. Other noises come from airplanes, trains, and construction work. Even tools for lawn care can add to the noise in neighborhoods. Poor planning can place loud industrial zones right next to homes.

Loud noise can change how living things live and grow. In humans, constant noise is linked to high stress and sleep problems. It can also lead to heart issues like hypertension or coronary artery disease. It can even cause tinnitus, which is a ringing in the ears.

Animals face their own set of hard jobs because of noise. It can make it difficult for them to find food or avoid predators. Noise can also interfere with how they navigate or have babies. In some cases, it can even cause permanent hearing loss in animals.

Scientists use special tools to measure how loud a sound is. They use a scale called decibels, or dB, to show loudness. This scale is logarithmic, which helps it cover a huge range of sounds. Most road traffic or construction stays between 70 and 100 dB.

If a person hears sounds above 85 dB many times, they might lose hearing. Researchers also look at frequency, which is the pitch of a sound. Humans hear between 20 Hz and 20,000 Hz. Some animals, like elephants or bats, hear sounds outside that range.

To get accurate numbers, experts use different ways to weigh sound. A-weighting is common because it mirrors how humans hear. It gives more importance to high sounds and less to low ones.

They also use C-weighting to measure short, loud bursts of noise. For long-term studies, they might use the day-night average level. This counts how much noise a community hears over a full 24 hours. Some measurements even add a penalty for noise that happens at night. This is because people are more sensitive to sound while sleeping.

There are many ways to collect this data today. One main tool is the sound level meter. It uses a microphone and an amplifier to catch sound waves.

Some workers wear a small device called a dosimeter to track noise. This stays with them throughout their entire work shift. Now, even smartphones can help with this work. The NIOSH developed a special app for Apple devices to help people. It can show the sound level in real time using a phone's microphone.

Noise pollution is the propagation of sound that has potential harmful effects on humans and animals.

It occurs when sounds are unwanted or too loud for the environment. The main sources of outdoor noise worldwide include machines, transportation, and propagation systems. In cities, traffic is often the primary source of noise pollution.

Poor urban planning can also cause problems. For example, placing industrial zones right next to residential areas can lead to high noise levels in neighborhoods. Other common sources include airplanes, rail transport, construction, and lawn care maintenance.

High noise levels can lead to serious health problems for humans. Chronic exposure to environmental noise is linked to cardiovascular disorders and hypertension, which is high blood pressure. It can also cause high stress levels, anxiety, and sleep disturbances. Some people may experience tinnitus, which is a ringing in the ears, or permanent hearing loss.

Animals are also affected by noise pollution. It can increase the risk of death by making it harder for them to detect predators or prey. Noise can also interfere with animal reproduction and navigation. In some species, it can even lead to permanent hearing loss.

Scientists use the decibel (dB) to quantify noise exposure. The decibel is a logarithmic scale used to relate physical sound intensity to human perception. This scale is necessary because the human ear can hear a vast range of sound intensities. Sound pressure level (SPL) represents the amount of pressure relative to atmospheric pressure during sound wave propagation. Sound intensity is measured in Watts per meters-squared and represents the flow of sound over a particular area. While these two concepts differ, both can describe loudness by comparing the sound to the threshold of hearing.

Researchers also measure frequency, which is the pitch of a sound. Frequency is measured in hertz (Hz) and reflects the number of sound waves sent through the air per second. Humans generally hear frequencies from 20 Hz to 20,000 Hz. However, sensitivity to higher frequencies often decreases as people age. Other organisms hear different ranges. For example, elephants can register infrasound, which are frequencies between 0 and 20 Hz. Conversely, bats can recognize ultrasound, which are frequencies above 20,000 Hz, to help them echolocate.

Because humans do not perceive all frequencies at the same loudness, researchers use frequency weighting.

A-weighting is the most common method because it mirrors the human range of hearing. It gives more weight to higher frequencies and less weight to lower frequencies. C-weighting is used to measure peak sound pressure or impulse noise, such as loud, short-lived sounds from machinery. Z-weighting, or zero-weighting, represents noise levels without any frequency weights applied. These different weights allow scientists to capture how noise actually affects human perception.

To manage public health, several specific metrics are used to describe long-term noise exposure. The equivalent continuous sound level (LAeq) measures the average sound energy over a specific period, such as for constant road traffic. Another metric is the day-night average sound level (LDN). This assesses cumulative exposure over 24 hours and adds a 10 dB penalty to nighttime noise because people are more sensitive to sound at night. In Europe, the day-evening-night level (LDN) is used. It separates evening hours from nighttime hours and adds a 5 dB penalty to the evening and a 10 dB penalty to the night.

Specialized tools allow for precise measurement of these sound levels.

A sound level meter uses a microphone, an amplifier, and a time meter to measure sound in the air. These instruments are categorized by the International Electrotechnical Commission into Type 1 for precision studies and Type 2 for general field use. For individual workers, a noise dosimeter can be used. This is a smaller, portable device with a microphone that attaches to the worker to monitor noise throughout a full shift.

Even smartphones can now assist with monitoring. The NIOSH developed a specific app for Apple iOS devices that allows users to calculate various measurements, including the maximum level and the total dose of noise exposure.

Noise pollution also has significant impacts on protected natural spaces. Researchers from the US National Park Service found that human activity can double background-noise levels in 63 percent of protected areas. In 21 percent of these spaces, human activity increases background noise tenfold. This increase has a major impact on the environment. In these loud areas, if a person could have heard something 100 feet away, they can now only hear it 10 feet away.