White Noise

White Noise

I live 500 yards from train tracks and 5 miles from a major highway.

The train typically whistles and rumbles, bumping along the track in a forceful, metal grinding push. The highway, in the meantime, sends out the normal grumbling hum-drum of heavy traffic as semi trucks move large loads, small automobiles whiz by them and occasional construction crews jack hammer.

Noise. It has been known to cause anxiety, tension or even illness, and prolonged exposure to high levels of noise can cause hearing loss, the USDA National Agroforestry Center says in its report "Leaf the Noise Out." Today, some people even regard noise as a form of environmental pollution. Yet, noise is a part of everyday life.

In the winter, I can hear the faint, consistent movement of highway traffic and I can actually see the train moving through the barren trees, in addition to hearing it. At night, the coyotes answer the train's whistles in long, low cries, adding to the rhythmless orchestra beyond my backyard.

But in the summer, all I can hear are the birds chirping and the leaves rustling as the wind blows through the trees. Peace and quiet.

Why? Because my house is surrounded by big, leafy, white noise machines known as trees. Trees muffle urban noise almost as effectively as stone walls, says the USDA National Agroforestry Center, adding that a properly designed buffer of trees and shrubs can reduce noise by about 5 to 10 decibels - or about 50 percent as perceived by the human ear.

The Arbor Day Foundation says it's actually the calming sound of the wind passing through the tree leaves that really helps muffle noise. Trees also provide habitat for birds, whose twitters add to the pleasant sounds.

R.J. Laverne, The Davey Tree Expert Co.'s manager of education and training, says it's more than just the noise trees audibly dampen that gives people the perception of a quieter space - the visual and atmospheric benefits help, too. He shares an example from the busiest and noisiest city in the world - New York. "In Central Park, the combination of the visual greenness and the darker, cooler, shaded space combined with that noise dampening effect gives your senses a calmer, quieter state of mind," he says. "If you set up a noise meter along the park pathway, it would probably still pick up the ambulance, police sirens, the hum of traffic or blowing horns, but when you are there you don't notice those sounds much anymore. Your senses focus on other things. So the noise may be there but your brain is choosing what to ignore and what to pay attention to."

For a maximum noise-reducing effect, tree care experts suggest planting a variety of both hedges or shrubs and taller trees to create a wall of foliage from the ground up.

But to achieve this result, choose species and planting design carefully. Those with dense foliage from the ground up in a range of shapes and sizes help reduce noise best. Some popular choices are cottonwood, poplar and aspen trees because their leaf shapes produce strong rustling sounds, but you'll want to check with a professional arborist for the best species for your area, sunlight and soil conditions. Evergreen varieties that retain their leaves through winter will provide better year-round protection, Laverne adds.

Also, plant a noise buffer close to the noise source rather than close to the area to be protected and as close together as the species will allow, the USDA National Agroforestry Center recommends.

Reducing the less welcome noises of everyday life - it's just one more benefit trees provide. "It's not one aspect of the tree individually that's so remarkable but the collective noise-dampening, temperature-cooling, interest-drawing, senses-calming aspect of trees that make us feel better," Laverne says. "That's the real beauty of trees."

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