Intrusive sounds on a landscape design project at times threaten to get in the way of the reason many of us make gardens, throwing cold water on the hope that they can comfort, heal, and create tranquility.
Sometimes the sound in the garden is not one of birds, wind in the trees or spring peepers. Instead, a walk through the green space is accompanied by the cacophony of downshifting trucks, fast traveling vehicles, sirens or train horns. What to do? First, be clear what plans can and cannot do. In the best of circumstances, often it is very difficult to mitigate sound appreciably using vegetation, unless you have a lot of space and a lot of plants and money. Visual screening is psychologically soothing, but some sounds are too intrusive to be impacted much by a few evergreens. If looking at the inside to get rid of sound on the outside, It is also hard to retrofit sound proofing into e.g.the walls of a bedroom.
The area where the sound is a problem may be a key to the strategy to try to offset it.
Sound is amplified when it bounces off buildings and hard surfaces, so that sound can be actually louder right beside the hard surface (house?) than say 20 feet closer to the sound/away from the house due to this characteristic. Vines on a building or wall help reduce reflection and muffle the sound a bit. Don't count on a row or two of shrubs or evergreens, however. Because sound travels like water, it can and will find a way through anything that is not super tight, or just go over the top of a fence. The source of the sound, pitch (high or low) and elevation of the sound are useful to observe. (second floor of the house being demo'd? street level?)
In the realm of relatively simple solutions, they may go beyond the garden and into the house. Moving the bedroom or sitting room to the opposite side of the house (whatever is key to where the owner spends time( location may turn out to be the least expensive and fastest way to start enjoying life again, since the lived- in areas may receive less noise. After doing so, changes to the landscaping to make wonderful view from that newly repurposed room wonderful could make use of the house itself as a sound barrier. There are also indoor and outdoor water features, and that might be a distracting and pleasant counter to the exterior ruckus.
Keeping the rooms as they are and trying a planted screening between the sound and the observer will have other positive psychological effects (people who have a tree view out the window in hospitals got well faster in one study). But out of sight does not mean that sound will not travel. Think of sound as moving similarly to water. It will find a way through most anything!
One other factor in sound mitigation is that higher-pitched sounds occur to the human ear as louder (more intrusive) than lower pitched sounds. It can be useful to listen to annoying sounds yourself to observe which sounds are most bothersome, considering whether pitch is a factor. Lower pitched sounds travel farther but are less intrusive, it is said. (This may be in the ear of the beholder, especially if a medical condition impacts how the sound is heard.)
In the example of train horn noise, I discovered that the Metro North train horns are required by regulation to blast between 96 and 110 dBa. Much discussion focused on whether the horns were "too loud," and the railroad countered that they were "within legal limits". None of this helped the family who recoiled in intense pain when a train horn was blasted not far from their home. After intensive research, I learned that within the past few years, the railroad had actually changed the tones involved in the horn blast (each railroad's horns have a distinctive set of notes), adding one higher pitched note. It was when the pitch got higher that residents who had lived along the railway started complaining about the noise, thinking it was louder. People do hear higher pitched sounds as louder than equally loud lower pitched sounds.
If sound mitigation is a prominent consideration in a landscape, remember that a lot of money can be poured into a poorly understood problem, and sound is frequently incompletely understood by designers. There are companies that will first analyze the characteristics of the sound, and then recommend an array of (their) solutions that will best address them. Few designers are accustomed to using them, but those who do are likely to find the shortest path to a satisfactory solution to an intransigent, intrusive problem. Not doing so might take a longer, more meandering route through a series of not-quite-satisfactory attempted solutions. In the end, starting the process with the mist intransigent problem and consulting with a sound engineer or specialist may save time and money in the long run and point the way to a technical solution that can be gracefully integrated into the rest of the landscape design.
The Root of the Matter is a blog created by Bespoke Gardening owner Christine Reid to share observations and in-depth insights from a seasoned professional gardener. Edible gardening, perennial gardens, and shrubs and trees — as well as the environments in which they live and the ways we care for them — are all areas of interest.