Soundproofing Yards and Dealing With Outdoor Noise
It Seems to Be Coming From Everywhere
Outdoor noises can come from all sorts of directions at the same time and may have many sources. They can also be reflected all over the place. People tend to look at what they think is the source and imagine that the sound is traveling along a straight line from the source to their yard. In reality it is likely that sounds have detoured, bouncing off buildings and other objects, arriving at your yard amplified and from a different direction to the source. The amplification which occurs is no different to sound amplification which happens when a murmur is channeled through a wind instrument and emerges at the other end as a trumpet blast. So your first step is to identify the source of the problem and the path that it is taking to get to your yard.
Words & Regulations Are Great Soundproofers
It might be possible that a nearby business or industry is exceeding acceptable noise levels or duration or operating at inappropriate times of the day. Sometimes you can solve the problem by simply raising the issue with the proprietor in a friendly manner. It may even pay to check with your municipal council and make sure that your noisy neighbors are not breaking local laws. People are often surprised to learn that there are a lot of laws protecting residential amenity (provided the noise is not from aviation which seems to be a law unto itself in many countries). I have seen laws which restrict the use of air conditioners after a certain time, prohibit leaf blowers and even outlaw pets like roosters and barking dogs.
Having exhausted logical commonsense approaches to reducing the noise you have two options for solving the problem. The first option is to create some sort of acoustic barrier in the yard. The second option is to return indoors and work on your internal soundproofing.
An Air Tight Yard!
It is impossible to make a yard airtight. You will always have to deal with flanking sound. Flanking sound is noise which wraps over, under or around your soundproofing structures. All of the principles of internal sound barriers and sound absorption still apply outdoors.
Lower frequency noise has a longer wavelength than high frequency and will require a higher and denser barrier. If for example if you are dealing with truck noise you would probably need a barrier as high as 12-15 feet (3.5 – 4.5 meters) or more. In most cases this is impractical or even against municipal building regulations, so it might be advisable to return indoors and work on your soundproofing there and be content with a quiet internal environment.
Is it a Baritone or Soprano Annoyance?
It is correct that higher frequency noises can be blocked by lower fences but there are some complications. Take level crossing train bells noise for example. This is fairly high frequency. You might expect that a lower fence would block the noise. Unfortunately the train companies have installed their bells at the top of ten foot poles which means you still have to install a 15 foot fence to have an acceptable impact on the noise. In an ideal situation you want to construct the fence at least eight feet higher than the source of the noise. This is less of a challenge when it is ground hugging car tail pipes but challenging when you are dealing with truck horns, and their roof top exhaust systems or even their loud engines which are quite high off the ground.
The Way of The Lotus Blossom
All is not lost when structural soundproofing seems out of the question. There are still a couple of innovative options. You can soundproof by creating more sound, particularly sound which is pleasing to the ear. For example one way to quickly deal with level crossing train bells is to install a splashing water feature in your garden; not to be confused with the quiet trickling Zen style installation. The sound of falling water will not only create a pleasant environment but it will interfere with the sound of train crossing bells and make them less noticeable. You can achieve a similar effect with wind chimes. Chimes are not quite as effective because they only work when the wind is blowing and the sound tends to be less random. The motivated soundproofing enthusiast might consider both chimes and a water feature and also external audio speakers for piping pleasant music into the yard. The application of these three strategies will sufficiently interfere with most annoying noise pollution and allow you to return to your yard for recreation, relaxation and entertainment. Another advantage of these noise masking options is that they are usually far less expensive and much more DIY than a massive fence.
Acoustic By Name Only
If you are going to construct a sensible acoustic barrier in your yard do make sure it is at a proper height and that it does not have any openings or gaps anywhere. The right height and absence of gaps are the two most important variables and the things that most people get wrong. Some do it yourself articles seem to promote the construction of acoustic fences at any height which frankly is a waste of time and effort. A fence won’t work just because it has word “acoustic” in its name! There are some proprietary acoustic fencing systems on the market and even with these systems it is important that you check the required height for your specific problem. Most respectable products come with data sheets.
Data Sheet is King
Data sheets should talk about an amount that the fencing system reduces noise. The amount is measured in decibels or dB. You should look for a system which will reduce the noise by at least 20dB. As a rule of thumb each 10dB is a halving of the perceived noise. Some products come with an STC rating. Again don’t consider a product with a rating below about STC 20. STC is a more useful summary of how a product responds over a series of sound frequencies. See if you can get the frequency chart for the product. Two products can work quite differently depending on the noise source and frequency response of the product. If you noise problem is lower frequency like trucks and “doof doof” music then you need a product which blocks more noise at lower frequencies e.g. between 50Hz and about 500Hz. So you would look for higher values against these frequencies on the STC chart. If your noise problem is at a higher frequency, like human voice, or small barking dogs, or train level crossing bells, then you would need better blocking at frequencies around 1000Hz to around 2500Hz. You would look for better performance at these higher frequencies.
Those Fences Are Big
An effective and relatively light weight material for acoustic fencing is steel sheeting, like the material used on deck roofs. Timber fencing performs well but it’s harder to create an airtight structure and the timber will be heavier and more difficult to work with. Whatever you use, remember that the structure is higher than usual and it will catch the wind. Make sure that your uprights are closer together and or thicker than usual and also bury them deeper into the ground.
If you already have a tall fence it probably has holes or gaps in and around it might not be made of the right material to block or absorb the offending sound. In situations like this you can consider retrofitting a product like mass loaded vinyl (MLV). This is a heavy plastic like membrane which is basically weatherproof. You can fix it to your existing fence and it will considerably increase the density of the fence and help block noise. MLV does not change the fact that you still need the right fence height.
If you live on a large property and you are able to build a mound of earth facing the problem this can be an effective and inexpensive way of creating a soundproofing barrier. Again the height has to be right and it can take a bit of effort to build an earth mound. Another option for large properties is a hay (straw) bale fence. There is endless Internet information these days on building with hay bales and they are cheap effective and quick, but they must be gap free and the right height.
Take Care Who You Listen To
Like all soundproofing issues there are endless myths about outdoor soundproofing. The most common one is the use of trees and shrubs. Trees and shrubs are pretty much ineffective except as visual screens. To some extent the sounds of the birds and wind through the leaves creates a masking sound like the water feature and chimes we talked about above.
Remember prevention is better than cure. If you haven’t bought your home and you are thinking of buying a nice bargain property which is a bit close to the trains, airport or freeway – think again. If you are even slightly sensitive to noise don’t put yourself through the nightmare of trying to solve noise problems for the rest of your days. Quality of life is more important than bargain real estate. Save a few more pennies and buy quiet. Don’t get lulled into a false sense sense of security about what constitutes acceptable quiet. Set your own standards and stick to them. Many property developments are noisy torture chambers and yet the brochures feature images of blissfully happy people living the life of their dreams. Not everyone cares about noise but if you’re someone who does, you need to look past the hype and ask if there is a 3am freight train passing nearby, or common plumbing running through the thin walls, or plans to construct a shopping mall behind your courtyard and so forth.
Source by Craig R Williams