The backyard is a place to relax and unwind in peace, especially after a tough week at work. It’s your personal space where you can sit back in tranquillity surrounded by verdant green and absorb the silence. However, this serene atmosphere is almost improbable in any urban environment as your moment of peace is disturbed by the beeping of car horns, whining noises stemming from a faulty water pump and dogs barking in the neighbouring property. You scramble to your feet, exasperated and frustrated that you can’t seem to have just 20 minutes of quiet in your own garden.
Most city dwellers experience this frustration and stress caused by noise intrusions, often on a daily basis. A 2003 study by Brown and Bullen found that up to 20% of dwellings in Australian cities (excluding Canberra and Brisbane) were exposed to traffic noise well above the recommended WHO limits; this percentage is likely to have increased in recent years given Australia’s expanding population and the recent building boom.
Noisy environments increase the risk of hearing loss and generalised anxiety disorder, and can even reduce lifespan. Fortunately, there are several solutions available to resolve noise intrusion issues, or at the very least, reduce the impact of intrusive noises.
Before investigating the ways in which noise interferences can be reduced, let’s understand how sound minimisation works in a backyard. What is the objective – sound attenuation or sound deflection? Sound deflection involves bouncing unwanted sound waves against a barrier back to the source. Though it is the most effective way to ‘kill sound’, it is also a lot harder (and expensive) to achieve. On the other hand, sound attenuation involves lowering the intensity of the sound by absorbing sound waves and is a more common solution adopted to deal with noise intrusion issues.
Things to consider when installing sound barriers
Height is an important consideration for sound barriers – the higher they are, the better they can prevent noise from rolling over the top. A wall barrier should ideally be about two metres high to sufficiently block out noise from an adjacent road. Remember, blocking the line of sight will help to block the line of sound. However, before doing so, check up on height and width restrictions mandated by most local councils.
Density and Rigidity
Height and length are important considerations when creating the barrier – the barrier should ideally be high and long with few spaces for sound to flow through. The density of the barrier will depend on the type of environment; for instance, buildings in close proximity to busy highways will require a denser and more rigid barrier, but a lower or smaller barrier may suffice for a residential street with less frequent, but nonetheless annoying noises.
A noise barrier should also extend all the way to the ground with no gaps. Openings at the base will allow extraneous noises from skidding cars, beeping horns and rattling washing machines to enter. Noise can also hit your backyard at angles, so it is advisable to stretch the barrier around corners and across as many sides of the garden as possible.
Proximity to the Sound
Sound protection barriers should be constructed as close to the noise source as possible (such as the neighbouring property or traffic). Alternatively, place the noise barrier close to a spot where one would normally sit, such as an outdoor table.
Sound barrier solutions
Wall of greenery
A simple wall of dense shrubbery is one of the most economical solutions as it will not only absorb noise effectively but also is aesthetically appealing. A green barrier needs to meet certain requirements to effectively block out sharper and louder noises. Ideally placed close to the source of noise or near areas that are frequented such as a backyard deckchair, the barrier should also wrap completely around the space that needs to be soundproofed to ensure maximum sound protection. Planting should be thick and very dense as sound waves can creep through the tiniest of openings.
Trees with thick branches and trunks that can reflect and absorb sound waves are recommended for planting. At least one row of tall evergreen trees, followed by an inner row of evergreen shrubs will ensure that your dense green barrier spans all seasons.
Dense vegetation tends to create psychological benefits for residents too; viewing greenery can help to reduce levels of stress that may be caused by the extraneous noises from outside. However, if the neighbourhood is particularly noisy, one will need a more impermeable barrier, such as a wall or fence to block out very loud noises. Even with very dense rows of greenery, one can only achieve a 25% noise reduction. An ideal solution will be one that combines a green barrier with a wall or fence.
Some homeowners prefer to install screens instead of a long solid wall or fence. A screen is a shorter and smaller version of a fence, cement or brick wall, but its effectiveness and cost will depend on the type of material used.
External screens are more economical and suitable than a proper wall for small outdoor seated areas requiring noise protection. Screens are often built closer to the seated area, rather than along the boundary line, since they are designed to block out noise for a particular area close to the sound recipient. Screens can be a very cost-effective solution for limited noise reduction requirements.
Timber fences are a cost-effective solution, but with a relatively short shelf life, and susceptible to fire and risk of rot. Timber should therefore be used sparingly, and never in bushfire prone zones. Easy to install, timber fences are simply not strong enough to withstand strong winds and tend to naturally fall apart easily with time, forcing numerous repairs and replacements upon the owner.
When using a timber fence to reduce noise, there should be no visible gaps between the slats. One solution would be to seal openings in wooden fences with an additional layer of timber.
Metal fences, such as those made from COLORBOND are sturdier and offer a more durable alternative to timber. Though metal fences cannot withstand strong winds, they tend to last long enough to be a good investment. However, metal fences rarely offer the aesthetic of timber fences and cannot be relied upon to add a grand appearance to the home.
Fences are likely to be less effective than a sturdy wall in blocking out noise. Their soundproofing qualities can be enhanced by padding up with noise reducing materials that absorb the sound rather than let it pass through.
Walls as sound protection
A dense wall made of solid brick or a composite material placed between the source of noise and receiver is typically the best solution to reduce the effects of intrusive noises. Due to their sheer mass and weight, bricks have excellent sound-reducing properties. Most dense walls can provide up to a 50% reduction in noise. Even if the wall is at a less-than-ideal height, the mass of dense concrete wall will help deaden the sound of traffic and other intrusive noises. Being highly durable, concrete walls can provide a long-lasting solution to backyard noise problems.
One will, of course, need to consider the cost factor when selecting traditional materials such as brick or cement. Those on a limited budget can opt for modular walls as a more cost-effective alternative to brick walls; at only half the cost of a regular brick wall, modular walls can help the homeowner achieve some real savings without impacting on the quality and sound reduction properties.
Ideal for higher walls and tight spaces in the garden, modular walls will suit most backyard settings. Quick installation is another advantage as one can put up modular walls in about a fifth of the time.
Beyond noise barriers, a well-designed backyard can go a long way to prevent noise intrusions from external sources. For example, building a deck on the opposite side of the home, as far away from the road as possible, is one way to reduce noise intrusions.
A garden oasis sitting on a lower level than the rest of the property would also work as an acoustic barrier, with retaining walls used to hold up the soil and mute incoming noises.
Water features as noise barriers
Water features offer an unusual solution to minimise sound disturbance, with added creativity. Water features have been used for centuries to minimise noise intrusions; examples would include fountains placed in the centre of courtyards during medieval times, or in serene Japanese gardens to fade out noises from the surrounding bustling city. The sound of trickling water is pleasant and has a calming effect.
Get professional advice for noise solutions
When it comes to minimising noise disturbance, the options are many and the final solution will depend on budget restrictions and personal preferences. Consider professional assistance from landscape or acoustic engineers who are trained to find the best acoustic solution for any type of environment, and can recommend the most suitable solution for a specific environment or application.