The whispering of trees, the babbling of brooks, the melody of birdsong. When you think of the sounds of the outdoors, it’s likely these sweet tones that first come to mind.
Now more than ever, however, when you step out your front door, when you take lunch in your office’s green space, and even when you take your children to play at the park, it’s not these sounds that you’re going to hear, but rather that of the drone of airplane engines, the clatter of freight trains, the whoop of horns and sirens, and the noise of highway traffic.
It’s a reality of modern life, but that doesn’t mean it’s healthy, and transit noise is taking a measurable toll on people’s physical and mental health (1-5). In fact, transit-related noise pollution is significantly increasing the burden of disease and avoidable mortality (5), even as it decreases the productivity of workers and the cognitive performance of students.
The good news, though, is that it is possible to reduce transit noise. The key lies in understanding how the physical environment affects transit noise, from amplifying to absorbing to diffusing it, and blocking it at the source.
From Low Roar to Constant Cacophony
As cities expand and rural spaces retreat, it can feel as if there’s nowhere to turn to escape the din of our modern, mobile world. Indeed, you don’t have to live in the heart of the metropolis to find yourself entrenched in and sometimes overwhelmed by transit noise. A brief glimpse at the research tells quite a tale. Sound studies have found, for example, that:
Interstate highway decibel levels average between 70 and 80 dB(A) at a distance of 50 feet.
Railroad traffic averages 84-93 dB(A) at speeds greater than 45 mph.
Commuter trains and mass transit (i.e. subway systems, elevated trains) generate an average of greater than 70 dB(A) (6).
The flyover of a jet at 1000 feet averages greater than 100 dB(A).
The noise levels of highway overpasses are 8 dB(A) greater, on average, due to reflection, exponentially amplifying noise levels above that which is experienced on the highway itself.
Motorcycle engines average approximately 95 dB(A), while an approaching subway train averages 100dB(A).
To put this in context, the volume of natural human conversation in a standard environment averages around 55-60 dB(A), whereas prolonged exposure to loud noise (i.e. greater than eight hours daily and/or 40 hours weekly) is associated with an increased risk of adverse mental and physical health impacts, including hearing loss, depression and anxiety, cardiovascular harms, cognitive impairments, etc.
Environmental and Occupational Safety Standards
Given all that has already been illustrated, the harmful impacts of transit noise on the sound environment are clear. Unfortunately, the sheer prevalence of traffic noise makes it easy to disregard and forget about. It can feel as if it’s merely an inevitable fact of contemporary life, something that cannot really be changed and, therefore, isn’t worth much thought or worry.
The reality, however, is that transit noise mitigation is both possible and necessary, as demonstrated by the various environmental safety standards implemented by OSHA, the EPA, and similar governing bodies.
OSHA, for example, has established that workers in the US be protected from workplace noise exposure levels that exceed 85 dB(A) averaged over an eight-hour work day. Safety protocols, including the mandatory use of hearing protection equipment and/or the installation of sound-mitigating devices, must be implemented in worksites that exceed these thresholds.
The standards established by the Environmental Protection Agency (EPA) are even higher. According to the EPA, ambient noise exposure should not exceed 70 dB(A) in an average 24-hour period.
Yet, as we’ve seen, from interstate and airport traffic to rail and subway systems, the sounds of mass transit regularly often greatly exceed the parameters established for human health, safety, and overall well-being. This has profound implications for the general population, but the ramifications are especially severe for the millions who live, work, and play in proximity to the highways, runways, railways, and subways of today’s world.
Exterior Sound Mitigation with FSorb
To be sure, the problem of transit noise pollution is as massive as the multifaceted transit system itself, but small, strategic steps can make an enormous difference. Exterior sound mitigation can be highly effective, provided you have the best and most appropriate materials. The goal, ultimately, is to absorb sound waves at the noise source, while preventing echoes and reverberations.
One excellent example is seen in creating a solution to mitigate reflected sound from a highway’s lower bridge deck that bounces off the upper bridge deck. While absorbing and blocking that reflected sound would provide a measurable improvement, it would not be perceived by the residents around the bridge because they could still see the traffic and hear it going by. A direct line of sight is also a direct line of sound, so in this case, a noise wall lined with FSorb is a better solution to reducing traffic noise for local residents.
On many highways, concrete barrier walls are installed to block the road noise from the residents adjacent to the highway. If the highway side of the walls were lined with FSorb, these walls would do a much better job of sound control, as sound can still bounce off the hard surface of the walls.
It is important to note that when addressing exterior noise, it is ideal to create a barrier around the noise source and then line the interior of that space with an acoustical absorber such as FSorb. What this does is reduce the amount of sound that escapes through the open “roof” of the space and reduce the amount of flanking sound that bends over the top of these barrier walls.
Enclosed spaces like a tunnel or similar structure can also benefit hugely from the use of FSorb. It can be installed directly to the walls or ceilings, suspended as a ceiling, installed as hanging baffles, or installed as protruding fins on the walls, and FSorb would dramatically change the level of sound received by those within the space.
FSorb offers a wide variety of sound mitigation solutions ideal for exterior spaces, including 2” exterior panels that can simply blend into the background. These panels can also be used to enhance the aesthetics of a space as they can be customized to an immense variety of colors, shapes, and patterns. They are made of recycled materials and are highly durable, ready to withstand the elements, from extreme weather to transit-related air pollution. Exterior FSorb is weather resistant, UV stable, and washable, making it ideal to maintain.
Additionally, FSorb is engineered using innovative techniques, which means that FSorb’s products aren’t just aesthetically pleasing and environmentally friendly, they’re also among the most effective and easily installed acoustic solutions available on the market today.
No matter how challenging the physical landscape, no matter how polluted the sound environment, it is possible to reduce transit noise. For commercial architects and engineers, this means the development of spaces that meet municipal regulatory standards, standards which often require outdoor areas to average 55 dB(A) or less.
Contact your local FSorb representative today to explore FSorb’s catalog of innovative exterior acoustic solutions and to discover how FSorb can help you create the ideal soundscape for your next outdoor design project.
At FSorb, we are motivated by improving human health and do so by creating eco-friendly acoustic products. Our mission is to help designers build beautiful spaces that reduce excess ambient noise while calming the human nervous system. With over 25 years in the acoustic business we stand behind FSorb as a durable, environmentally friendly, and low-cost product. If you want an acoustic solution that is safe to human health at an affordable price, then we are your resource.
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