The Sunday before Easter was beautiful here — an absolutely perfect day for working leisurely in the yard. About ten minutes into our afternoon, the peace and quiet of the day was shattered by the the deafening roar of a neighbor’s leaf blower running full blast. The first hour was unpleasant but tolerable. The second hour moved up a few notches to annoying, the third hour was miserable and by the fourth, our neighborly politeness gave out and we checked out the city’s noise ordinance. Had it been a one time occurrence, I could have let it go, but he’s spent every weekend since then running that machine for hours on end. The noise is threatening to keep us prisoners in our house all summer.
Although we realize and decry the effects of smog-filled air or contaminated water, there is another form of pollution that we may not take seriously. Noise pollution, which is explained as “unwanted or excessive sound that can have deleterious effects on human health and environmental quality” has become a significant problem not only here in the United States, but also world-wide. It poses health risks for humans and is now known to play a role in the alteration of our world’s ecosystems and the potential extinction of some species.
Sound is measured in decibels which are the units used to measure the intensity of a noise. Total silence is 0 dB, a normal conversational voice is 60 dB and a gas-powered lawn mower or leaf blower is 80 – 85 dB. An approaching subway car or the noise at a sporting event can average 100 dB, while American music events, especially rock concerts can easily reach 120 – 140 dB.
Hearing loss from sustained noise levels has been documented for centuries. Medical records of hearing loss by copper workers and blacksmiths exist from as far back as the 1700s. Today, experts advise that prolonged exposure to sounds at 85 dB or above can not only result in hearing loss and damage to the ears, but it can also contribute to other serious health conditions. Anxiety, depression, high stress levels and increased aggression are tied to noise pollution, as are headaches, fatigue and high blood pressure.
Noise pollution has been termed a “modern plague” for children. For infants and young children, constant noise can affect language skills, including speech development, and cognitive functioning. Studies have shown that with continued exposure to noise, difficulties with reading, problem-solving, short-term memory and listening skills can continue into adolescence and then adulthood.
This “modern plague” is now recognized as a threat to wildlife — both large and small — as well. Science has confirmed that sounds made by ships and those from underwater drilling affects marine life. Whales are known to stop vocalizing while dolphins, porpoises and other species stop foraging. Spawning patterns are disrupted and migration paths are altered. At the other end of the spectrum, in a controlled study at Mississippi State University, lady beetles exposed to loud noise significantly reduced their consumption of aphids. A lack of pest control by beneficial insects could reduce crop production by as much as 25% and upset the ecological balance.
Unfortunately, with urbanization on the increase, the reality is that many of us are subjected to unwanted and potentially harmful noises on a daily basis. Although they may not be completely eliminated, a few landscaping techniques can help reduce unwanted noise and restore an aura of peace and quiet to your home.
There are four common approaches to sound modification that designers use: absorption, deflection and reflection, refraction and masking.
Often used in large areas, this method reduces sound intensity by trapping sound waves within plant material. The leaves, branches and even bark of plants absorb sound. Plants with many branches, large, fleshy leaves and rough bark work well for sound absorption. Broadleaf evergreens like holly and viburnum are excellent choices since they retain their foliage throughout the winter and have branches that extend from the very bottom to the top. To achieve maximum benefit, the barrier planting should be quite dense, as close to the source of the noise as possible, and planted in thick layers.
DEFLECTION AND REFLECTION
Fences and other partitions can block sound waves from entering a space and cause them to bounce back toward their source. Rigid, dense walls (think masonry like brick or concrete) send the waves straight back toward the source, while flexible walls (like corrugated metals or fiberglass) tend to vibrate and cause sound waves to bounce off in a multitude of different directions. Combining plant material for absorption with walls and fences creates an even stronger sound barrier and visually softens hard surfaces.
When sound waves hit flat, hard surfaces and are trapped in a confined space, they tend to become magnified and cause echoes. Those same sound waves are naturally dissipated, or scattered, eliminating echoes whenever they hit a rough surface. Adding grass or ground covers, vining plants and overhanging trees can help to cover flat spaces with rough surfaces and reduce the magnification of sound waves. Although many of today’s designs include sleek, modern materials for looks, understand that these types of surfaces can work to heighten noise pollution in high traffic, urban spaces.
Including a source of white noise in the landscape, especially if it is combined with the other methods of noise abatement, can be especially effective. Water features that include splashing or falling streams can cover unpleasant sounds and can offer an almost irresistible sense of peacefulness. Some plant materials also offer white noise as the breeze blows through their leaves. Ornamental grasses provide both subtle sound and enticing movement while trees like aspens rustle gently in the breeze. Welcoming birds, frogs and other wildlife to the landscape brings in the sounds of nature to obscure harsh city sounds.
Whether it is a constant problem or an intermittent annoyance, noise pollution can be addressed with a few fundamental landscaping techniques. Share your concerns with your designer; a qualified professional like those at Embassy Landscape Group will be able to offer you effective solutions that will help reduce the city clamor and fit your budget.