Helena Joyce
Plants can be used to reduce noise pollution through a phenomenon known as sound attenuation, which is the reduction of sound intensity. This is achieved through a combination of sound absorption, deflection, refraction, and masking. The flexibility of plant material allows them to vibrate when sound waves hit them, transforming the waves into other forms of energy and deflecting them in different directions. Certain types of plants, such as those with rough bark and thick, fleshy leaves, are particularly effective at absorbing sound due to their larger surface area. In addition to their noise-reducing properties, plants also provide aesthetic benefits and can create a more welcoming and tranquil environment in buildings such as offices, hotels, and medical facilities.
| Characteristics | Values |
|---|---|
| Absorption | Plants absorb sound through their stems, leaves, branches, wood, and other parts. Rough bark and thick, fleshy leaves are particularly effective at sound absorption due to their dynamic surface area. |
| Deflection | When sound waves hit flexible plant surfaces, they vibrate and are transformed into other forms of energy, as well as being deflected in different directions. |
| Refraction | Plantings that cover large surface areas, such as vines on walls, lawns, ground cover plantings, and green walls, help refract sound by bending sound waves around plant structures. |
| Masking | Plants like oaks and quaking aspens rustle in the wind, creating pleasant masking sounds. The presence of vegetation can also attract wildlife, such as songbirds and crickets, contributing to masking noise pollution. |
| Sound Attenuation | Vegetation reduces noise pollution through sound attenuation, accelerating the reduction of sound intensity as energy dissipates over distances. |
| Noise Barriers | Strategically placed trees and plants act as noise barriers, reducing noise pollution by absorbing, deflecting, refracting, and masking sound waves. A 100-foot-wide tree barrier can reduce noise by 5 to 8 decibels (dBA). |
| Plant Placement | For optimal noise reduction, plants should be placed around the perimeter of a space, allowing sound to reflect off walls and into the plants. |
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What You'll Learn
Plants absorb, diffract and reflect sound
Plants are effective at reducing noise pollution through the processes of sound absorption, diffraction, and reflection. These natural sound barriers can be used in both indoor and outdoor settings to create a more tranquil environment.
Firstly, plants absorb sound. Plant parts such as stems, leaves, branches, and wood all contribute to sound absorption. In particular, plants with rough bark and thick, fleshy leaves are highly effective at absorbing sound due to their large surface area. The greater the number, size, and surface area of plants, the better their ability to absorb sound. For instance, a tactically designed 100-foot-wide tree barrier can reduce noise by 5 to 8 decibels (dBA).
Secondly, plants diffract sound. When sound waves hit rigid materials, such as walls, they are reflected back toward the source. However, when sound waves encounter flexible materials like plants, the material vibrates, transforming the sound waves into other forms of energy and deflecting them in different directions. This is similar to how carpeting in a room helps to eliminate echoes by absorbing and diffracting sound waves. Vines on walls, lawns, ground cover plantings, and green walls are excellent at diffracting sound, creating a more pleasant acoustic environment.
Lastly, plants reflect sound. By placing plants around the perimeter of a space, sound waves are reflected off the walls and into the leaves of the plants, reducing the overall noise level in the room. This is especially effective in open-plan offices, where plants can serve as attractive and functional partitions to reduce unwanted noise.
In addition to these processes, plants also contribute to noise reduction through masking. While it does not interfere with sound waves, masking creates more pleasant sounds, such as the rustling of leaves or the chirping of birds, that help to offset noise pollution.
Overall, by absorbing, diffracting, and reflecting sound, plants provide a natural and aesthetically pleasing solution to reducing noise pollution, improving the acoustic comfort of indoor and outdoor spaces.
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Vegetation reduces noise through sound attenuation
Vegetation reduces noise through a phenomenon called sound attenuation, which is the reduction of sound intensity. Sound attenuation occurs as the energy of sound waves is dissipated over long distances, causing a decrease in sound intensity. Vegetation speeds up this process by absorbing, deflecting, and refracting sound waves.
Absorption
Plant parts such as stems, leaves, branches, and wood all absorb sound. Rough bark and thick, fleshy leaves are particularly good at sound absorption due to their large surface area. The number, size, and surface area of plants will affect their ability to absorb sound.
Deflection
When sound waves hit a rigid material, such as a wall, the waves are reflected off the surface and bounce back. However, when sound waves hit a flexible material like plants, the material vibrates, and the sound waves are transformed into other forms of energy and deflected in different directions. This deflection helps reduce the intensity of sound waves.
Refraction
Sound waves can be refracted as they pass through vegetative barriers, bending around plant structures. Plantings that cover large surface areas, such as vines on walls, lawns, ground cover plantings, and green walls, are excellent at refracting sound.
In addition to these processes, vegetation also helps in masking sound. The rustling of leaves, the swaying of branches, and the sounds of wildlife attracted to urban vegetation, such as birds and insects, create pleasant sounds that offset noise pollution.
The placement of plants is also important for effective noise reduction. Plants should be placed around the perimeter of a space, rather than at the center, to maximize sound reflection into the leaves of the plants. Additionally, a combination of different types of plants with varied heights and dense foliage can improve noise reduction.
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Plants can be used as sound barriers
Plants can also help with sound deflection. When sound waves hit a rigid material, like a wall, it does not vibrate, and the sound waves are reflected off the wall and back towards the source. However, when sound waves hit a flexible material, like plants, the material vibrates, and the waves are transformed into other forms of energy and deflected in other directions. Vines on walls and the sides of buildings, for example, help refract sound.
In addition to absorption and deflection, plants can also provide sound refraction. Sound waves can create echoes when bouncing off solid surfaces, but these echoes can be reduced by covering these surfaces with plants. Lawns, ground cover plantings, and green walls are all excellent at refracting sound.
When choosing plants for a sound barrier, it is important to select plants that will thrive in the local environment and are tolerant of air pollution if placed by roadways. Noise barriers should also have diverse structures, including varied heights and textures, to prevent gaps. A combination of mixed broadleaf and evergreen conifer plants, for example, can lower noise by 10 decibels. Hedges are another effective landscape form that provides noise abatement and beauty.
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Using plants to reduce indoor noise levels
Plants can be used to reduce indoor noise levels in several ways. Firstly, plants absorb, diffract, reflect, and refract sound waves. The balance of these processes varies with the frequency of the sound and the room's physical properties. Plant parts such as stems, leaves, branches, and wood all contribute to sound absorption, with rough bark and thick, fleshy leaves being particularly effective due to their dynamic surface area. The greater the number, size, and surface area of plants, the better their ability to absorb sound.
Secondly, plants act as physical barriers to sound waves, deflecting them and preventing them from reaching the listener. This is similar to how carpeting in a room with solid floors helps to eliminate echoes. Vines on walls, lawns, ground cover plantings, and green walls are all effective at refracting sound. When choosing plants for sound deflection, consider using a combination of evergreen and deciduous plants for year-round noise reduction.
Thirdly, plants can mask unwanted noise by creating sounds that are more pleasant to the human ear. For example, species with thick or papery leaves, like quaking aspen or oaks, rustle gently in the breeze, while bamboo produces white noise. The presence of vegetation can also attract wildlife, such as songbirds and crickets, that make pleasant sounds.
Finally, plants can enhance air humidity through the process of transpiration, which can help to trap and reduce ambient noise.
When using plants to reduce indoor noise levels, it is important to consider their placement. Plants should be placed around the perimeter of the room rather than in the centre, so that sound reflects off the walls and into the plants' leaves. Additionally, in open-plan spaces, screen plants can be used as partitions to absorb noise and provide an attractive alternative to traditional dividers.
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Plants help refract sound
Plants are effective in reducing noise pollution through a phenomenon called sound attenuation, which is the reduction of sound intensity. Vegetation hastens the normal attenuation mechanisms of absorption, deflection, refraction, and masking.
The type of plant and its characteristics play a role in refracting sound. Rough bark and thick, fleshy leaves are particularly effective at absorbing sound due to their larger surface area. Additionally, the size and number of plants impact their ability to refract sound. Bigger plants with more foliage, such as large trees or bushes, can create effective sound barriers.
Strategic placement of plants is also crucial for optimal sound refraction. Plants should be placed around the perimeter of a space to allow sound waves to reflect off the walls and into the plants. For example, vines on walls, lawns, ground cover plantings, and green walls are excellent at refracting sound. When used as screens or partitions, plants can effectively reduce noise levels in open-plan offices or indoor spaces.
By understanding the properties of plants and their strategic placement, we can harness the power of plants to refract sound and create more tranquil environments, reducing the adverse effects of noise pollution.
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Frequently asked questions
Plants help in reducing noise pollution by absorbing, deflecting, refracting, and masking sound waves.
Some plants that can be used to reduce noise pollution include spruce, poplar, beech, oaks, quaking aspen, bamboo, arborvitae, and privet.
Plants should be placed around the perimeter of a space, rather than in the center, so that sound reflects off the walls and into the leaves of the plants. In addition, mixed plantings with varied heights and broadleaf specimens are more effective at reducing noise pollution.
A tactically designed 100-foot-wide tree barrier can reduce noise by 5 to 8 decibels (dBA). In addition, mixed broadleaf and evergreen conifer plants can lower noise by 10 decibels, and a berm combined with plant material can reduce noise by 6-15 decibels.
