Landscaping for privacy and noise reduction

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How to Landscape for Noise Reduction

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Ambient noise can be a fact of life in many urban and suburban neighborhoods. Whether the sounds are from the street, an air conditioning unit, or a neighbor’s pool, blocking them out creates an increased sense of privacy and is beneficial to stress levels.

Fortunately, there are ways to landscape for noise reduction by using smart hardscape and plants.

1. Install a Good Fence

A tall fence helps reflect sound waves that originate from behind the fence and the more solid the wall, the more effective it will be. Masonry walls such as brick, stone, or stuccoed concrete are best. A solid wood fence without gaps is less effective than masonry but can certainly help.

The most important aspect of a noise-reducing fence is that the construction lacks gaps that sound waves can sneak through. Most wood fences have gaps between the soil and the bottom of the fence and, unfortunately, sound waves will creep through that space.

For severe problems, special fences that have noise absorbing blankets installed on the inside of the slats aren’t your most attractive option, but they do work and can be made more visually-appealing with plants. Note that fences higher than 6-feet-tall require a permit in San Diego.

2. Install a Water Feature

Running water creates white noise that is pleasing to the brain and helps mitigate undesirable sound. Yes, California is in a drought but it is still possible to install a water feature in an environmentally-sensitive manner. It must have a recirculating pump to keep water moving without draining the fountain and requiring new water to be added.

Instead of filling water features with a hose, use repurposed fresh water from rain barrels or inside the home. As you wait for hot shower water to arrive, fill a bucket with the cold water and use it to fill your water feature.

The water feature also doesn’t have to be large to be effective but it does need to be close to the listener to have maximum impact. Place it in outdoor seating areas or near the house itself, depending on the noise. Also consider when you’ll need the noise. Is it during rush hour? Do you need it only when enjoying your outdoor living space? Or consistently? Many pumps have timers while others run on solar energy that might not power the pump through a full 24-hour cycle.

Fountains can drown out noise levels of lawn mowers, consistent traffic and other noises that are on the same frequency levels. They can’t do much for honking horns, sirens and the like.

3. Use Tall and Strategic Plantings

While some homeowners are convinced that tall plantings actually block out noise, experts in psycho-acoustics (the study of sound perception) suggest that it’s more of an out of sight, out of mind concept, because sound waves can creep through openings in a dense hedge or planting of trees. A thick tree truck, of course, helps deflect some sound, but it usually isn’t going to be enough to make a huge difference.

We say go with whatever works so plant away. What experts do seem to agree on is that if you can’t see the source of the sound, it won’t bother you as much. If your street is subject to noise from semi-trucks, make sure that your barriers are tall enough so that you can’t see them passing by.

4. Noise-blocking Plants

If you are opting to use plants, a row of dense hedges is your best bet for blocking sound but if you can layer plants in front of that—all the better. Make sure that the hedge chosen has branches that grow to the ground as any gaps there will let in sound waves. Boxwoods are very commonly used as noise-blocking hedges as they can easily be pruned into shape.

Many homeowners choose to plant hedges in stone or paver decorative or retaining walls as this look tends to be more aesthetically pleasing. Plus, tall hedges don’t require permits.

5. Use Plants That Create Natural Sound

Do you have a breeze? The rustle of leaves in the wind helps mitigate sound by creating white noise. Look for evergreen trees with big leaves as those that lose leaves seasonally won’t be effective when they are bare. In Southern California, even palm tree fronds or water-wise plants like tall leucadendrons can create a bit of ambient noise in a light wind.

6. Sink Your Outdoor Living Space

When it isn’t practical to sound proof the entire yard, put these techniques in place in a designated outdoor entertaining area. A sunken outdoor living space at even just a few feet below ground level will benefit from a small wall of soil to help deaden sound.

But if the living area is three feet below ground level and six-foot fencing is at ground level, you’ve also just created a nine-f00t sound barrier in a way that might avoid permitting issues (check local building requirements). Pair this with lush plantings and you’ve just created a mini oasis.

7. Wind Chimes

One of the most inexpensive ideas on this list, wind chimes have been used for centuries in zen gardens for improving the energy in a space. Soothing melodies from wind chimes mask unwanted sounds and are thought to offer benefits ranging from eliminating laziness to inviting prosperity into the home.

Choose a wind chime material to round out the elements in your yard. For example, soften the look of metal by adding wood wind chimes. Or, if you’d like to adhere to refer to the principles of feng shui the exact location of the wind chimes will play an important role.

8. Purchase Outdoor Speakers

Use music to divert guest attention away from road traffic and other distractions. High quality speakers wired into your outdoor living space are likely the most visually appealing and high-tech solution. However, a quality portable speaker that you can pop your mobile phone on to will do as well. While you wouldn’t want to leave it on perpetually, weather-proof outdoor televisions are rising in popularity, should you want to catch a game.

Your Turn…

How do you landscape for noise reduction?

A main concern for many homeowners when it comes to their property, is seclusion. Whether your home is close by a neighbor, or your house is situated on a busy road, landscaping for privacy is often the main priority. We meet with many clients every year that are looking for ways to use landscaping to block road noise, or landscaping ideas to block out neighbors.

When it comes to creating an outdoor space, there are a lot of factors that go into the overall design. Looking at the property as a whole, and the purpose of the project, determines what it will entail. With swimming pools, patios, and outdoor dining areas, most homeowners want these outdoor rooms to feel enclosed. Rather than being on display from the street, or from a bordering property, landscaping is used to create walls. We always tell our clients that landscaping is what ties together all the hardscape and outdoor living space into one. It is the final touch of color and texture to blend the home from it’s indoor to it’s outdoor space.

Best Plants for Noise Reduction and Landscaping for Privacy

  • Arborvitae
  • Willow Trees
  • Cypress
  • Hollies
  • Boxwood
  • Juniper
  • Flowering Trees – dogwood, magnolia, plum, cherry

There are eco-friendly benefits to using landscaping for privacy as well. Rather than choosing to add a large expensive or high fence to your property, trees bring in a natural and beneficial border. Many homeowners find high fences to be an eyesore. It will require permits from the town and change the view of your property. With landscape screen walls, you are able to add a natural and beautiful border to your property that will only enhance it’s curb appeal. It is a softer approach to adding walls to your backyard. Many of these trees used in screening will add a green color to your property, often lasting year round even through the winter months. From foliage to snow fall, to flowering spring and summertime, a greenery wall is a perfect backdrop to a backyard space.

Large plant materials and trees will work to block road noise and act as a buffer to surrounding sounds. It also provides an enclosed and comforting border to the backyard. With proper care and maintenance, landscaping will only continue to grow and thrive over time, growing with the property and providing more and more privacy and noise reduction over time.

It is important to work with landscape professionals when choosing the best landscaping for privacy and noise reduction. If you are unsure which plants are best for your climate or location, they will be able to assist you in choosing what will work best. This is an investment and you should have a professional to help make sure your money is being best spent. Planting large trees on your property requires proper irrigation, as well as choosing the right specimens for sun or shade location. If you are interested in adding landscaping for privacy to your property, or are interested in learning more about options with landscaping to block road noise, feel free to contact us today. We look forward to helping you create a peaceful and private space.

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Landscaping to Reduce Traffic Noise

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Traffic noise can really put a damper on an otherwise tranquil and relaxing backyard living space. There are a variety of landscaping methods that can help homeowners reduce unwanted traffic noise. Shrubs, hedges, trees and fences are all fantastic tools to accomplish this goal. In addition, it is often helpful to add some soothing white noise. Listed below are a few great landscaping tips for those looking to reduce traffic noise in their yards.

Traffic Noise Reduction Tips:

  • Plant evergreen trees.
  • Utilize tall hedges.
  • Plant varying types and sizes of shrubs.
  • Install a privacy fence.
  • Add white noise.

Plant evergreen trees

Most people think that just planting trees is enough to reduce unwanted noise. Regular trees will only block noise when they are full of leaves. Also, many trees only have leaves on their higher branches. Evergreen trees are perfect for noise reduction because their leaves don’t fall off seasonally, and many evergreen trees have leaves and branches that extend all the way to the ground.

Utilize tall hedges

Tall hedges are great for blocking noise from a busy street. In addition, they also act as a privacy screen. Hedges do take a little time to grow, but they are a perfect choice for any homeowner who plans on spending a lot of time in their yard. Hedges require some regular maintenance as they grow.

Plant varying types and sizes of shrubs

Shrubs are great for noise cancellation. Homeowners will have a variety of shrubs to choose from depending on their geographic location. Hardy native varieties make great choices for those who want low-maintenance noise cancellation. Native varieties often require very little care and water. It may be helpful to speak with a local nursery prior to purchasing and planting shrubs.

Install a privacy fence

A privacy fence is an incredibly effective landscaping tool. Depending on how small the yard is, a privacy fence can be constructed in just a few days. Traditional wood-plank fencing makes a good economical choice for reducing traffic noise. Homeowners with larger budgets should consider brick and stone fences for more effective traffic-noise reduction.

Add white noise

A great way to reduce traffic noise is to add soothing white noise to an outdoor living space. Fountains are a great way to bring a peaceful sound into an otherwise noisy backyard. A fountain also makes a beautiful visual addition to any backyard garden or patio.

Combination approach

A combined approach is the best way for homeowners to reduce traffic noise in an outdoor living space. Planting trees, hedges and shrubs is a great start. Dedicated homeowners should also build a privacy fence and add some soothing white noise. When combining all of these noise-cancelling methods, the end result is a much more tranquil and relaxing outdoor living space.

Planting Noise Blockers: Best Plants For Noise Reduction In Landscapes

The most visually appealing way to block noise is with a dense growth of plants. Noise blocking plants are especially useful in urban areas where refracted noise from hard surfaces, such as buildings and pavement, are problematic. An advantage to using plants as noise blockers is that they absorb sounds best in the high frequencies that people find most annoying. Let’s take a closer look at using noise reducing plants.

Planting Noise Blockers

You should plant noise reducing plants as you would a hedge. Space them so that there won’t be gaps between the plants when they reach maturity.

You can even install dense layers of plants to provide optimum noise protection. Begin with a row of shrubs nearest the noise, and plant a row of taller shrubs or trees behind them. Finish with a row of showy shrubs that face your home or garden. Choose the inside shrubs for their visual impact, fragrance, fall color and other desirable features. Consider how the appearance of the shrubs will complement your overall landscape design.

For best results, plant noise blocking plants on a berm. Mound the soil as high as possible with a flat top at least 20 feet wide. The ideal height is 3 to 4 feet with sides that slope about 10 percent. A combination of a berm and a dense planting can reduce noise by as much as 6 to 15 decibels.

Shrubs and Trees as a Noise Barrier

Evergreen shrubs make the best plants for noise because they provide year-round noise reduction. Broadleaf evergreens are more effective than narrow-leaf plants and conifers. Choose trees and shrubs with dense branches that reach all the way to the ground. Plants, such as hollies and junipers, that have thick branches at ground level provide excellent noise reduction.

Additionally, a solid wall is more effective at blocking noise than plants. Combine form and function by using plants along a wall.

When the plants don’t reduce noise enough, try adding sounds that mask unpleasant noises. Flowing water is very effective at masking unpleasant noise. A garden fountain or waterfall is well worth the time and expense of installation. Weatherproof speakers allow you to add soothing sounds to the garden too. Many are designed to mimic natural garden features such as rocks.

News

Have you ever experienced noise pollution? Whether you live close to a street or are in a closely-built neighborhood, you may have some unwelcome noise that you’d like to remedy for the human ear. Below is a list of the best trees to block sound and an explanation of how trees reduce noise pollution.

Plants are the perfect antidote to noise pollution and sound absorption, and of course, they offer many other benefits. These include increasing home value, reducing air pollution, and beautifying your landscape. In order to boost the noise-reducing benefits of trees, you’ll need to choose ones that feature thick, dense foliage and that can be planted closely together. You need a year round noise reduction fence planted close to the area.

Why sound barrier trees planted along the roads reduce noise?

The University of Tennessee Agricultural Extension Service suggests that planting two or three rows of sound absorbing plants can effectively reduce noise levels by more than seven decibels! According to SF Gate, “the ideal noise barrier hedge is dense and tall enough that you can’t easily see through or over it. The effect is bolstered by planting vegetation in multiple rows and multiple tiers, such as an overstory of tall trees, an understory of tangled shrubs, and a ground cover. Read more about landscaping around trees.

You can enhance your noise barrier even more by first installing an earthen berm of several feet, then planting atop and around it.”

Wondering which plants would work best as noise reducers? Here are some of our top picks.

Noise Reducing Plants:

Oak leaf holly gives a great textural appearance in any landscape.

Oakleaf Holly:

Looking for a stunningly beautiful tall hedge to help block noise sources? The Oakleaf Holly is an elegant hybrid holly featuring a tall, pyramidal form. Its foliage is distinctive and charmingly similar in shape to that of an oak, and unlike many other hollies, the Oakleaf will set red berries without needing a pollenizer. As the tree reaches maturity, the lower branches lose their vertical turgidity, giving the mature tree a pyramid shape.

Your Dwarf Burford Holly hedge will take a few years to establish and grow up to 8 feet tall. Space them accordingly.

Dwarf Buford Holly:

This handsome shrub features an attractive and dense growth habit that makes for a lush addition to your yard while still being low maintenance. The thick foliage will help sound block when planted as a hedge and will also add a distinguished feel to any landscape. Bonus: birds love to come eat the Dwarf Buford’s red berries in the winter! More plants with red berries.

The pink flowers of the Indian Hawthorn attract birds, bees, and butterflies to your landscape.

Indian Hawthorn:

The Indian Hawthorn’s glossy, dark green foliage makes an excellent noise-reducing low hedge. As beautiful as it is useful, this unique shrub is well known for its beautifully decorative flowers, glossy evergreen foliage, and naturally rounded shape. It grows clusters of fragrant pink white blossoms intermittently from spring through summer that are followed by dark, bluish-black berries that persist through winter.

Noise Reducing Trees:

Leyland is of the most dense evergreen tree to create a living privacy fence.

Leyland Cypress:

One of the most popular noise-reducing trees, the Leyland Cypress will become a tight, dense barrier for view, absorbs sound or wind reduction when planted as a hedge. A very fast growing tree, the Leyland Cypress grows 2 to 3 feet annually, reaching 40 to 60 feet at full maturity when planted in full sun. It’s bright emerald green foliage remains striking year-round and is soft to the touch. It grows very densely, maintaining its slender, conical shape naturally. A belt of trees is the best sound reduction with cypress trees.

Cryptomeria is an excellent choice for landscapers across the United States as it can grow in USDA zones 5-9.

Cryptomeria Radicans:

The Radicans’ habit is tall and slender, and it offers year-round beauty as a privacy screen that helps surrounding noise reduction. It is a quick grower, reaching 12 to 16 feet tall within 5 years of planting. Eventually, this fast grower can get up to 40 feet in height and 20 feet wide at full maturity.

This handsome growing evergreen tree features foliage that is exceptionally dense, dark green and feathery, therefore offering good contrast to its blue-leafed evergreens. The large leaves give it the appearance of a Christmas tree.

Planting privacy trees in your outdoor living space provide an attractive and versatile way to decrease sound and traffic noise levels. We prefer them over wooden fences because of their home-improving appeal. Noise reduction landscaping is economical and the best way to improve your peace of mind and the environment! Another great tip is to add a water feature with a circulating pump to create white noise.

Want to chat more about finding the right trees to block sound waves for your landscape? Contact us or leave a message in the comments, we’d love to help!

What trees do you have planted to help reduce sound?

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Garden Myths – Learn the truth about gardening

With houses being built closer and closer together, people are more concerned about noise pollution than ever before. There is much talk about planting trees and shrubs between the homes to reduce noise levels, both people noise and traffic noise. How effective are trees in reducing noise?

Trees will reduce noise pollution levels, but only if planted correctly.

trees reduce noise pollution

Noise Pollution

Noise is the vibration of air molecules, a kind of wave effect in the air. You would think that as this wave of noise reaches a tree that is in full leaf, the wave would stop, and the noise would not go past the tree. After all you can’t see any light through the tree. Unfortunately, that is not what happens. Waves can actually travel around objects. As the noise wave hits a leaf, it goes around the leaf and continues on.

I know this is a bit scientific, but the net effect is that a single tree or bush has very little effect on noise levels. If you need to reduce noise from a neighbor and your homes are close together, the only thing that really works is something solid, like a fence. Even fences with a lot of holes or spaces in them have limited effect on noise pollution.

Are Trees Effective?

In some situations trees will reduce noise levels up to 50% but to be effective you need a tree barrier that is at least 50 feet deep. It also needs to be longer than you might expect, and it needs to consist of both trees and shrubs that start at ground level.

Trees can be used as a noise barrier, but not for the typical home owner. Plant trees to enjoy them, and learn to live with the noise from neighbors – or move!

2) Using Trees and Shrubs to Reduce Noise Pollution: http://blog.arborday.org/using-trees-and-shrubs-to-reduce-noise/

2) Photo Source: Mrs. Gregerson’s Biology Class Blog

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Trees as Sound Barriers

It is not an unknown fact that noise can reach unhealthy levels in urban areas. Cities across the world have acknowledged the impacts of noise pollution and enacted by-laws and practices to battle this increasing environmental issue.

Noise abatement has become an important consideration for many municipalities as they constantly look at ways of suppressing and dampening surrounding noise from nearby roads, railways, and airports. Urban trees can be used as sound barrier to reduce noise pollution. As with planting for wind or visual barriers, the selection and arrangement of the trees is key to a successful outcome. Where solid barriers such as fences are frequently used as sound barriers, trees and shrubs can also be effective. Where space permits, thick strips of vegetation in conjunction with landforms or solid barriers can reduce highway noise by 6 to 15 decibels (D.I. Cook). Because trees absorb more high frequency noise than low frequency, this makes them ideal for use as sound barriers.

Published results on the effectiveness of trees as sound barriers vary enormously, however, a study by Huddurt in 1990 shows that in some instances noise can he reduced by 6 dB over a distance of 30 meters where planting is particularly dense. Leonard and Parr (1970) and Reethof (1973) found that a dense belt of trees and shrubs between 15-30 m wide could reduce sound levels by as much as 6-8 dB. Cook and Van Haverheke (1972) found reductions in noise level of 5-10dB for belts of trees between 15-30m wide. Research also suggests that wide plantings (around 30 meters) of tall dense trees combined with soft ground surfaces can reduce apparent loudness by at least 50%.

How Trees Reduce Noise

Noise reduction is achieved by either deflection or absorption of the noise or a combination of the two (to be effective they should be as close as possible to the source of the noise). Most hardscape barriers on the other hand, work solely by deflecting sound (example 1 in above image). Earthen berms are often used in combination with trees and shrubs to deflect and absorb sound when the available space is limited (example 2). Large-leaved deciduous species may be more effective at reducing noise during spring and summer but evergreens will provide better results year-round.

In regards to tree size, it has been proven that noise reduction tends to increase with tree height up to 10-12m, after which it tends to decrease. This is a result of lower branches dying and allowing sound to travel more easily. Noise reduction is correlated with the width of a belt of trees, meaning the wider it is the greater the noise reduction. A screen placed relatively close to a noise source is more effective than one placed close to the area to be protected. However, at midway between the source and receiver, noise reduction is least.

There are several factors to be considered before deciding to create a tree barrier against noise.

  • Noise is more effectively reduced by completely screening the source from view.
  • A noise barrier should be planted as close to the noise source as possible.
  • Wide belts of high density trees and shrubs are required to achieve significant noise reductions.
  • Effectiveness of noise reduction is closely related to the density of stems, branches and leaves.
  • For year-round noise reduction use broadleaved evergreens or a combination of coniferous and broadleaved evergreen species.
  • Soft ground is an efficient noise absorber. Cultivating ground before planting and the addition of well-rotted organic matter to the soil surface may also help to reduce noise whilst vegetation becomes established.

Using Trees and Shrubs to Reduce Noise

Noise from vehicles and others sources can reduce one’s enjoyment of being outdoors. Dense, tree buffers can reduce noise to levels that allow normal outdoor activities to occur. For instance, a 100-foot wide planted buffer will reduce noise by 5 to 8 decibels (dBA). If one uses a barrier in the buffer such as a landform can significantly increase buffer effectiveness (10 to 15 dBA reduction per 100-foot wide buffer with 12-foot high landform).

The table and guidelines below provide general design considerations when implementing a buffer for noise control.

Key Design Considerations

• Locate buffer close to the noise source while providing an appropriate setback for accidents and drifting snow.

• Evergreen species will offer year-around noise control.

• Create a dense buffer with trees and shrubs to prevent gaps.

• Select plants appropriate for the site conditions.

• Select plants tolerant of air pollution and de-icing methods.

• Natural buffers will be less effective than planted buffers because they are usually less dense.

• Consider topography and use existing landforms as noise barriers where possible.

Estimating Setback Distance from Noise Control Buffers

A setback distance from the noise control buffer may be necessary to achieve the desired levels of noise reduction along a high speed road. The charts below can be used to estimate this setback distance. For example: An outdoor recreational site near a highway needs to be located to meet the desired noise levels of 60 to 65 dBA. If 100-ft wide tree/shrub buffer is used, the site needs to be 100 to 200 feet behind the buffer. The site can be located immediately behind the buffer if a 12-ft high landform is incorporated into the buffer.

This post is an excerpt from Conservation Buffers: Design Guidelines for Buffers, Corridors, and Greenways. Check out the Guide to learn more about designing buffers to improve air water quality, protect soil, enhance habitat, enhance economic productivity, provide recreation opportunities, and beautify the landscape.

Jul 18, 2017

Best Trees And Plants That Help Reduce Noise For Commercial Properties

nlmlawn in Trees & Plants

Everyone enjoys a little peace and quiet, but the nature of a commercial property sometimes makes it difficult to create a space that provides serenity. Noise reduction becomes an issue, leaving employees left with no option other than sitting in their car while on a lunch break. Perhaps you’re a hotel manager of a property with a pool. Not having sufficient privacy could result in guests not willing to go for a swim. So what can you do to help block out noise?

Trees and plants are the best (and most visually appealing) way to help with noise reduction, and can easily be incorporated into your commercial landscaping plan. But which ones are best? Here are several suggestions of trees and bushes that are best for blocking out noise.

1. Trees that help block noise.

Evergreens are the best trees to use when looking for some privacy or to drown out noise. They typically grow fast (several feet a year) and are dense. Below are two excellent choices of evergreen trees you can use. They look great on any property and are low maintenance. Keep in mind that it’s best to plant them in rows to create a ‘wall’ to achieve maximum results.

Leyland Cypress

Known for their rapid and thick growth, the Leyland Cypress is one of the most popular trees used to achieve privacy. Their thick growth helps absorb sound and block out noise. Leyland Cypresses are also tough, capable of withstanding mild drought, flooding, and snow. They grow between 3 to 5 feet a year, reaching up to 50 feet tall and 15 to 20 feet wide.

Arborvitae

Also in the evergreen family, Arborvitae can also help drown out noise. But they are much slimmer than Leylands–growing only about 12 to 14 feet tall with a spread of 3 to 4 feet–so they’ll need to be planted much closer together in order to achieve the same results of a Leyland Cypress. Arborvitae are also resilient, but they’re known for their cold hardiness, making them a favorite among northern landscaping companies.

2. Shrubs that help block noise.

If you’re not looking to plant full trees, or don’t have the room, there are plenty of plants and shrubs you can use instead. Evergreen shrubs are ideal, since they’ll provide year round noise reduction. Plants like hollies and junipers have broad leaves and thick branches.

Hollies

As a shrub, holly bushes provide excellent noise reduction at the ground level. They grow thick with large leaves and lots of branches, so they’re ideal for planting around an outdoor patio where employees can enjoy a quiet environment, but still be able to see beyond the property.

Spruce

Spruce’s are also evergreens, and there are many types of spruce shrubs from which to choose to help block noise. Be aware that some of them are better suited for different climates. The Globe Blue is best for zone 2 (the Southern part of the United States), while the Fat Cat Norway is suitable for colder climates.

3. White Noise

Once you’ve got your trees and plants established, if there’s still an issue with noise, you can consider having a water fountain installed. The sound of flowing water is soothing and will help with noise reduction, and is always an attractive feature for outdoor patios.

By Adam Vaughan

The spiny pincushion cactus has been found to emit ultrasonic sounds

Jose A. Bernat/Getty Images

Although it has been revealed in recent years that plants are capable of seeing, hearing and smelling, they are still usually thought of as silent. But now, for the first time, they have been recorded making airborne sounds when stressed, which researchers say could open up a new field of precision agriculture where farmers listen for water-starved crops.

Itzhak Khait and his colleagues at Tel Aviv University in Israel found that tomato and tobacco plants made sounds at frequencies humans cannot hear when stressed by a lack of water or when their stem is cut.

Microphones placed 10 centimetres from the plants picked up sounds in the ultrasonic range of 20 to 100 kilohertz, which the team says insects and some mammals would be capable of hearing and responding to from as far as 5 metres away. A moth may decide against laying eggs on a plant that sounds water-stressed, the researchers suggest. Plants could even hear that other plants are short of water and react accordingly, they speculate.

Read more: Root intelligence: Plants can think, feel and learn

“These findings can alter the way we think about the plant kingdom, which has been considered to be almost silent until now,” they write in their study, which has not yet been published in a journal.

Previously, devices have been attached to plants to record the vibrations caused by air bubbles forming and imploding – a process known as cavitation – inside xylem tubes, which are used for water transport. But this new study is the first time that sounds from plants have been measured at a distance.

On average, drought-stressed tomato plants made 35 sounds an hour, while tobacco plants made 11. When plant stems were cut, tomato plants made an average of 25 sounds in the following hour, and tobacco plants 15. Unstressed plants produced fewer than one sound per hour, on average.

It is even possible to distinguish between the sounds to know what the stress is. The researchers trained a machine-learning model to discriminate between the plants’ sounds and the wind, rain and other noises of the greenhouse, correctly identifying in most cases whether the stress was caused by dryness or a cut, based on the sound’s intensity and frequency. Water-hungry tobacco appears to make louder sounds than cut tobacco, for example.

Read more: Plants have evolved forgetfulness to wipe out memory of stress

Although Khait and his colleagues only looked at tomato and tobacco plants, they believe other plants may make sounds when stressed too. In a preliminary study, they also recorded ultrasonic sounds from a spiny pincushion cactus (Mammillaria spinosissima) and the weed henbit dead-nettle (Lamium amplexicaule). Cavitation is a possible explanation for how the plants generate the sounds, they say.

Enabling farmers to listen for water-stressed plants could “open a new direction in the field of precision agriculture”, the researchers suggest. They add that such an ability will be increasingly important as climate change exposes more areas to drought.

“The suggestion that the sounds that drought-stressed plants make could be used in precision agriculture seems feasible if it is not too costly to set up the recording in a field situation,” says Anne Visscher at the Royal Botanic Gardens, Kew, in the UK.

Read more: Trees seen resting branches while ‘asleep’ for the first time

She warns that the results can’t yet be broadened out to other stresses, such as salt or temperature, because these may not lead to sounds. In addition, there have been no experiments to show whether moths or any other animal can hear and respond to the sounds the plants make, so that idea remains speculative for now, she says.

If plants are making sounds when stressed, cavitation is the most likely mechanism, says Edward Farmer at the University of Lausanne, Switzerland. But he is sceptical of the findings, and would like to see more in the way of controls.

Farmer adds that the idea moths might be listening to plants and shunning stressed ones is a “little too speculative”, and there are already plenty of explanations for why insects avoid some plants and not others.

Reference: bioRxiv, DOI: 10.1101/507590

Read more: Wonder what your plants are ‘saying’? Device lets you listen in

Article amended on 16 December 2019

We clarified what Edward Farmer would like to see; and we corrected what happens in cavitation

More on these topics:

  • plants
  • biology
  • agriculture

Researchers have detected, for the first time, plants emitting airborne sounds when they are stressed

According to a study published in the pre-print website bioRxiv, a team of Israeli scientists recorded tomato and tobacco plants producing sound frequencies which humans cannot hear in stressful situations—such as when they experienced a lack of water or their stems were cut.

The team identified the sounds with microphones placed around 10 centimeters (around four inches) away from the plants, although the scientists say the noises could potentially be heard several feet away by some mammals and insects, such as mice and moths.

Previous research has shown that plants respond to stress by producing several visual, chemical and tactile clues. For example, stressed plants may differ in color and shape compared to unstressed plants. Meanwhile, some are also known to emit substances known as “volatile organic compounds” in response to drought or being eaten.

Furthermore, plants exposed to drought stress have been shown to experience cavitation—a process where air bubbles form, expand and explode inside tissue that transports water. These explosions produce sound, but they have only ever been recorded using devices directly connected to the plant.

The latest study, meanwhile, is the first to identify plants making sounds which can be detected over a distance. And the researchers say that cavitation could potentially be the source of these sounds.

“These findings can alter the way we think about the Plant Kingdom, which has been considered to be almost silent until now,” the authors wrote in the study.

The team detected the tomato plants making 35 sounds an hour on average when they were exposed to drought conditions, while the tobacco plants produced 11. When the stems of the plants were cut, the tomato plants made 25 sounds an hour on average and the tobacco plants produced 15. As a comparison, unstressed plants made less than one sound per hour on average, according to the study.

The team say that while they only tested tomato and tobacco, it’s possible that other plants could also produce sounds, adding that the latest findings could have implications for agriculture.

A picture taken near Sivens in Lisle-sur-Tarn, southwestern France on August 31, 2017 shows tomato plants. REMY GABALDA/AFP via Getty Images

“Plant sound emissions could offer a novel way for monitoring crops water state—a question of crucial importance in agriculture,” the authors wrote in the study. “More precise irrigation can save up to 50 percent of the water expenditure and increase the yield, with dramatic economic implications.

“In times when more and more areas are exposed to drought due to climate change, while human population and consumption keep increasing, efficient water use becomes even more critical, for both food security and ecology,” they said. “Our results, demonstrating the ability to distinguish between drought-stressed and control plants based on plant sounds, open a new direction in the field of precision agriculture.”

According to Anne Visscher from the Royal Botanic Gardens, Kew, in the U.K., the idea that the sounds could be used in precision agriculture is “feasible” although she urges caution regarding the Israeli team’s suggestion that other animals could hear the sounds at a distance, New Scientist reported.

Meanwhile, Edward Farmer from the University of Lausanne, Switzerland, told the magazine that although cavitation is the most likely way a plant could make sounds when stressed, he said more research was needed to validate the team’s conclusions.

Plants May Not Have Ears, But They Can ‘Hear’ Way Better Than We Thought

The flowers are listening, according to new research – well, in a sense, at least.

Scientists have found evidence that plants can actually hear the buzz of passing bees and produce sweeter nectar in response to entice the flying insects in. And flowers are technically their ‘ears’.

Based on observations of evening primroses (Oenothera drummondii), the team behind the new study discovered that within minutes of sensing the sound waves of nearby bee wings through flower petals, the concentration of the sugar in the plant’s nectar was increased by an average of 20 percent.

The flowers even seemed able to tune out irrelevant background noises, such as the wind.

This capability could well give some plants an evolutionary advantage, say the scientists, maximising their chances of spreading pollen.

“Our results document for the first time that plants can rapidly respond to pollinator sounds in an ecologically relevant way,” write the researchers from Tel-Aviv University in Israel.

The scientists went into the experiments with a hypothesis in place: that plants can indeed pick up the vibrations of sound waves, and that this might be part of the reason many plants’ flowers are bowl shaped, to better trap the sounds.

Across several experiments involving more than 650 evening primrose flowers, nectar production was measured in response to silence, sound at three different frequency levels, and a recording of the buzzing noise made by bees.

Sure enough, both the field recording of buzzing bees and the low-frequency sounds that closely matched the recording were enough to change the mix of the nectar in just three minutes. The silence and the high and mid frequency sounds had no effect.

The team also tried the experiments with plants that had some flower petals removed. No change in nectar production was noted, indicating that it is indeed the flowers that have the job of the ears.

These lab tests were backed up by observations the team made in the wild.

“Plants have plenty of interactions with animals, and animals both make and hear noises,” one of the team, Lilach Hadany, told Ed Yong at The Atlantic.

“It would be maladaptive for plants to not use sound for communication. We tried to make clear predictions to test that and were quite surprised when it worked out.”

Pushing out sweeter nectar means bees may well stay feeding for longer – increasing the chances that they’ll pick up pollen – and also makes it more likely that the insects will return to flowers of the same species in the future.

This sweetness boost needs to be timed perfectly though, to make it worth the flowers’ while – and that’s exactly what seems to be happening.

As yet the work hasn’t been peer-reviewed, and it’s not clear precisely how the vibrations are being decoded and turned into a trigger for sweeter nectar production, but it’s an intriguing first step into the study of how plants react to sounds around them.

We’ve already seen past research into how plants respond to touch and daylight, and now we can add acoustic vibrations to the list.

Next, the researchers want to look at how plants might respond to other sounds and animals, including humans.

“Some people may think, how can hear or smell?” one of the study authors Marine Veits told National Geographic. “I’d like people to understand that hearing is not only for ears.”

The research has been published on the pre-print server bioRxiv.

Blocking Road Noise with Trees and Shrubs

Many people choose to add a fence to a property is to increase privacy in a yard or to block street/road noise. Depending on your property this may or may not completely work. If you are trying to block out road noise but your home sits on a hill above the road chances are good that you are not going to be able to block it all out with the traditional fence. Fencing regulations make this difficult by limiting how high you can build, and for good reason. If we were all allowed to build fences as tall as we like we would more than likely end up with some very ugly neighborhoods. If you find yourself in this situation a great work around is to use trees and shrubs acting as a fence with no height regulations. A fence will help out with the majority of noise but in some situations you must go beyond the fence. As always, it is good to ask yourself a few questions before you get started on a project like this.

First, how urgently do you need to block out the noise? Is it immediate or can you live with it while you wait for the trees to grow? This will make a difference on how much you spend and what kind of plants you purchase. Some plants grow faster than others so it is good to do your research and find out what will be best for your situation.

How much noise is there? Do you need really thick trees or just something to block visibility? This will also have an impact on what kind of plants you purchase and how much money you spend. If you are trying to block out really loud road noise you will want a thicker tree/shrub that will absorb much of the sound. If sound is not an issue but you are trying to block a view you may not need such a thick shrub.

What kind of budget are you on? Plants range is cost and can be a make it or break it for your project. If you are looking for plants that are already grown to a certain height then you will be spending more vs. plants that are still small.

Like most projects it is important to do some research before you go out and buy. The last thing you want to do is spend money on a plant/tree that loses its leaves in the fall. What good is that going to do? So be sure to take the time and learn about what will fit your needs best. Below are some great resources on trees and shrubs that could help out on your project.

Fast Growing Trees – A list and review of trees that grow quicker than others

Best Trees to Block Road Noise – A short E-how article recommending trees to block noise.

Guide to Soundproofing a Home – Another E-how article on steps to soundproof a home

A practical Guide to Noise Control – An 160 page E-book guide to cutting down noise.

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Many people are looking for ways to better soundproof their home. What you might not realize is that there are some indoor plants that are good at absorbing sound. You might be wondering if they work, so I did a little research.

What are the best sound absorbing indoor plants? The indoor plants that work best at absorbing sound are:

  • Ferns
  • Baby’s Tears
  • The Peace Lily
  • The Rubber Plant
  • The Weeping Fig
  • Norfolk Island Pine
  • The Fiddle Leaf Fig
  • The Areca Palm
  • Janet Craig
  • The Money Tree

Plants will effectively help absorb sound in your home. I was skeptical at first, but I decided to experiment with these plants in my house to see if they made a difference with sound absorption. I was pleasantly surprised by what I found.

Do Plants Help to Absorb Sound?

There’s quite a bit of research on the subject, but the short answer is yes. The flexible and porous nature of indoor house plants acts as natural sound reducers.

There are three ways that house plants can reduce the sound in your home or office: deflection, absorption, and refraction.

While looking at the research surrounding the issue, I found that most people don’t understand the sound absorbing benefits of houseplants. However, they really do help with absorbing sound.

I found out that plants, depending on how many and their placement, can absorb up to 50% of the sound energy being produced in your home or office. You heard me right; I said 50%. That’s quite a reduction.

How Plants Reduce Indoor Noise Levels?

As I mentioned above, plants reduce noise levels through three different methods: deflection, absorption, and refraction.

  • Deflection – Sound waves tend to bounce around off hard surfaces. That’s where all that added noise comes from. Walls are rigid and will amplify sound, while plants are flexible and help to deaden the sound by breaking up the sound waves into other forms of energy.
  • Absorption – Plants are great at absorbing sound because of the leaves, branches, and wood. Wood is a great sound absorber. Have you ever walked through a forest and been amazed at the silence? That’s because the trees are absorbing all the ambient noise.
  • Refraction – Refraction is taking away the echoes of the sound bouncing off the hard surfaces. Plants will help to refract this noise and eliminate the echoes which are responsible for much of the added noise in your home or office.

How to Use Plants to Reduce Noise

When using plants to reduce noise, don’t be afraid to get a few more than you first planned. Look for a variety of plants, some bigger and some smaller. The more plants you have means there is more overall surface area to help reduce noise.

When I first started experimenting with plants, I used the planters that came from the nursery. However, once I switched out some of the standardly sized pots with larger ones, I noticed a big difference.

The added soil helped to increase the surface area. Eventually, this extra space allowed my plants to grow larger than they would in the smaller planters, which increased their sound absorption properties.

Make sure that you put the plants around the perimeter of the area where you want to reduce the noise. What this does is help to trap the sound as it bounces off the walls into the plants. If you put them in the center of the room, the sound will still get through and will bounce off the hard surface of the walls.

Best Sound Absorbing Indoor Plants

Ferns (Nephrolepis Exaltata)

Ferns have a lot of surface space to help reduce sound. Their wide leaves spread out and cover quite a bit of area. I love the look of ferns, so it was a win-win for me. Ferns are a pretty dense plant as well, and they do a great job of absorbing the noises in my loudest room.

I like to place them near the corners where they can trap sound from a variety of angles. They help to absorb sound and they are great at deflecting sound into the plants that surround them.

Baby’s Tears (Helxine Soleirolii)

The golden Baby Tears. Source

Baby’s Tears are a dense plant that looks almost like moss. The plant has a way of draping itself over the pot, and makes a great sound reducer when elevated off the ground.

I experimented with a few different placements for these plants and I found that they are the most effective when hung higher off the ground.

The problem with this is that they are missing a large part of the room where sound can easily be reflected. I hung mine lower from the ceiling which allowed the plants to hang down and catch the areas that non-hanging plants miss.

Peace Lily

The peace lily is a great sound absorbing plant you can put in your home. Their true noise absorbing properties are in their thick, broad leaves.

The thick leaves help with all three sound absorbing properties. I found that these plants are extremely easy to care for and they don’t require too much upkeep.

They absorb some of the sounds with their leaves and do a great job of bouncing the sound to the other plants I placed around the room as well. This is by far one of my favorite noise reducing plants.

Rubber Plants (Ficus Elastica)

Source

Rubber plants are often tall. They can grow up to three feet and have broad, thick leaves that reduce noise.

The beauty of this plant is just how big it can get. Rubber plants cover a large surface area which only serves to enhance their sound absorbing properties.

I found that I could place them in a large pot, right on the floor anywhere around the room. The combination of the leaves and size acted as an acoustic wall of sorts. Because of their size, you don’t need too many of these to feel the effects of their ability to block out the noise.

Weeping Fig

Weeping Fig plants are excellent noise blockers because of how dense the plant is. Look at it this way, the more density a plant has, the more it can block out the noise.

The plant has some thick, arching branches that help to give it a full appearance. The branches and leaves combined are great at absorbing the sound.

I placed a couple of these on stands to fill in the middle area of my walls where I was noticing I had some gaps. The sound would bounce off the walls and these plants would just eat it up. No ringing, no echo, and a solid plant for helping reduce noise.

Norfolk Island Pine

Source:Mokkie

Remember my analogy about walking in a quiet forest? Pine trees are great at reducing sound, and the Norfolk Island Pine is an excellent addition to your noise reducing plant collection.

The pine needles grow out in a crisscross pattern. What this does is to help trap the sound within the plant itself. Their needles might seem small, but the surface area that they cover aids in their effectiveness as a noise blocker.

Fiddle Leaf Fig

The fiddle leaf fig is another plant with broad, thick leaves. They can grow tall, and the cupped shape to the leaves make for an effective sound absorber.

The bottom of the tree is narrow, so they work best when placed in an area where they are surrounded by other plants that will fill in the bottom area where sound can get through.

Since they grow tall, set the pot on the floor and let the large leaves stretch up where they will do a great job of catching sound in the middle wall area.

Areca Palm

Palm trees are known for their broad fronds. These plants can stretch out and fill in areas that might be difficult to cover otherwise.

They are dense at the bottom which helps to deflect the sound up into the fronds. These plants cover a large surface area since the fronds like to spread out, especially as they grow larger.

These plants are good as a standalone plant if you have an area that needs some sound absorption and don’t have a lot of space for multiple plants.

Dracaena Janet Craig

These plants are excellent sound absorbers because they are dense from top to bottom. The leaves of the plant start to spread out from the base up to the top.

Since the leaves tend to drape down, they help to cover a pretty wide surface area. When sound hits a Janet Craig plant, it bounces around inside the plant. Ultimately, this is what you want.

The sound will get in, but it won’t get out. Since the leaves do such a good job of absorbing sound, you don’t need too many of these. I found that the one I used in my room was more than enough.

Money Tree (Pachira Aquatica)

Money tree plants are great filler plants for areas where you need a little more coverage. They have a very thick stalk that helps to push sound up into the wide leaves.

You can plant these as a single or as multiples in one pot. The leaves on these like to stretch out like a canopy. Any sound that finds its way up into the canopy of these plants gets trapped inside like an umbrella.

I used a couple of these in my room to fill in spaces where I didn’t want a huge plant, or make my room look like a rainforest.

How Else Can I Reduce Noise

There are other ways to reduce noise in your home as well. There are soundproofing curtains that can help absorb the sound. There’s a reason why movie theatres have curtains inside.

Another item I like is floor underlayment that goes under wood or laminate flooring. When I installed my new laminate flooring, I put some of this as the base layer over the concrete and under the flooring. This helped to reduce the amount of sound that used to echo from the floor.

A very easy fix is to get some soundproofing weather stripping to go around your windows and doors. I did this recently and saw a nice reduction in the absorption of sound in that particular room.

Related Questions

Are plants affected by noise? Most house plants aren’t overly affected by noise. There are some cases where too much ambient noise can limit the overall growth of a plant, but for the most part, plants are resilient and can withstand quite a bit of noise without any negative effects.

A Good Wall, Even if It’s Made of Plants, Can Reduce Highway Noise

A reader’s good question was the impetus for this week’s column. The problem she writes about is not only tough to control, but is becoming steadily worse and widely shared. If you live near the Beltway or any other major thoroughfare in this area, you too might have noticed how the decibel levels have increased in recent years.

A buffer of mixed plants can absorb and deflect sound waves. The mix of plants is important because different types of leaves reduce different types of noises. How much noise control they provide depends on the intensity, frequency and direction of the sound, and the location, height, width and density of the planting.

Mixed broadleaf plantings at least 25 feet thick and conifers 50 to 100 feet thick can drop noise levels by up to 10 decibels. For year-round noise reduction, plant a mix of evergreens such as arborvitaes, spruces, pines and hollies. To be effective sound barriers, these trees must have foliage that reaches to the ground.

Deciduous plants are also effective for noise abatement, but only when foliage is present. Like evergreens, these must also have foliage from the ground up to really do the job. Thickets of sassafras and paw paw have been found to be relatively effective for this purpose.

Include lawn or some other ground cover in shady areas. Turf grass or other low vegetation has a muffling effect on sound, compared with surface areas of bare soil or various paving materials, which are more likely to bounce sounds off their surfaces.

But noticing noise might be as much psychological as physical. When you don’t see the source of the sound, there’s an implied screening that makes it less apparent. So the use of plantings between you and the noise at any width is valuable for most home landscapes. That’s also a good reason to install something to try to camouflage noise. Installing a fountain, music and screening might further contribute to a quieter yard.

Flowing water can be a wonderful foil for noise, especially if it has a cascading flow and makes a splashing sound. There are free-standing, tiered water features that offer some degree of noise screening.

Music in the garden — classical, country, jazz or whatever you prefer — can have a profoundly soothing effect on your surroundings, and make the world around you seem to fade away. Some weatherproof speakers specially designed to be used outdoors have a very good sound. I even have seen high-quality speakers in housings designed to look like ordinary garden rocks.

Despite these measures, however, noise control is most effective when a solid barrier is used. When the Montgomery County Office of Environmental Policy and Compliance checked decibel levels from behind a wide band of plants, highway noise didn’t change significantly from summer to winter.

So does foliage account for more than psychological noise screening? The jury is out on the issue because so much depends on how far you are from the source of the sound, plant height differences and the presence of other noise barriers, such as soil, concrete or wood.

Consider the following example: Next time you’re driving down the highway, note the surge of noise that fills the car when you crack open the window just a fraction of an inch. It doesn’t take a large opening for noise to get through. In just this way, any opening in mixed plantings will allow lots of noise through. This illustrates the difficulty of protecting your landscape from undesirable sounds exclusively with plants.

The most effective measures you can take against noise with plants depends more on the configuration of the soil than the tree or shrub you’re putting into it.

The best way to reduce noise is to establish a soil berm for your plantings: Large mounds of soil thickly planted, as described above, do a much better job of blocking sound than plants alone. Make your berm as high as possible, at least eight feet tall and 20 feet wide, and as long as your property line. A solid, well-planted berm can cut auto and truck noise by 70 to 80 percent and substantially reduce sounds from playgrounds, sporting activities or factories.

You can also effectively dampen noise for a small townhouse or postage-stamp-sized property with a fence or wall. Install a fence or wall with no openings that is tall and dense enough to shield outside clamor. It will work just like the barriers you see along the highway. These types of barriers are far more expensive than your typical garden-variety fencing because they have to be completely sealed.

If you can’t get your local transportation department to do the job, get as close as you can to building that type of barrier. It must be solid, with no spaces to let sound through. A tongue-in-groove style of wooden fence constructed of unfinished 2-by-10-inch lumber built to be as tall as possible would serve this purpose. Architects will have more . This might be a special-order item for residential use, but you could have one built by a local custom fence company, carpenter or mason. Be sure to check local codes and permitting requirements for fences and walls before proceeding.

As increasing urbanization, particularly vehicular traffic, has added to the clamor in our environment, the field of noise-abatement engineering has grown rapidly. Look at any highway with adjacent residential neighborhoods and you see more miles of sound walls being erected every day to protect the ears of nearby residents. They really work as long as they’re constructed along both sides of the road.

It is the government’s responsibility to erect these tall, dense barriers to help abate noise in our communities, but property owners can take the smaller steps of installing dense plantings, berms, fences and walls.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site, www.gardenlerner.com.

Perhaps not as effective at blocking sound, but certainly better looking, are walls of trees and smaller plants.Sound-barrier walls such as have become a common sight in the D.C. area.

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