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The effects of frequent loud noise can be extensive; increasing stress, interfering with sleep and much more. The World Health Organisation (WHO) recommends outdoor sound levels of 50 dBA to prevent people becoming &#;moderately annoyed&#;, but many of the noises we encounter on a daily basis exceed this recommendation.
Incorporating acoustic barriers can reduce the amount of noise pollution in an area, either through reflecting or absorbing sound from the source. To help you understand what to expect from acoustic fencing, we&#;ve answered the most common questions about it here:
First of all we would strongly recommend contacting a qualified sound engineer who will specify the type, length and most critically, the correct height of the barrier to ensure optimum performance is achieved. There are a variety of factors which should be taken into consideration before purchasing your acoustic barrier, which include the surrounding environment, the proximity of the noise source to the barrier and the receiver. A realistic dB reduction could be between 9-15 decibels &#; this reduction to the human ear represents a halving of sound. If you consider road traffic rates as 70dB and conversational speech at 60dB, that&#;s a dramatic drop in volume! Be aware that although the term 'sound proof fencing' is often used, a fence cannot completely sound proof an outdoor space, but it will make a considerable difference.
There are a host of factors that differentiates a certified acoustic fence from a normal domestic fence but the key differences are the following
An acoustic barrier requires a minimum surface mass density of at least 10kg per M2. This is because a mass of this weight will start to reflect noise back, rather than allowing it to simply travel straight through&#; a domestic fence produces circa 4kg per M2 whereas the Jakoustic barrier produces 25kg!
An acoustic barrier needs to be completely imperforate so sound cannot travel through &#; a domestic fence by nature will generally have some gaps throughout it&#;s design, after all, it&#;s designed for screening only and not to reduce noise.
An acoustic barrier should have a life of at least 20 years. Be sure to check that the fence actually comes with a guarantee and not just an expected lifespan. Fortunately for our customers' peace of mind, all of Jacksons products, regardless whether it&#;s an acoustic fence or not, are guaranteed for 25 years against rot, insect attack, and manufacturing defects.
As long as acoustic fencing meets certain requirements, it will provide sound reduction. The effectiveness of an acoustic fence is determined by five main factors:
Material density: greater mass provides greater sound reduction.
Barrier construction: good structural integrity is critical to performance. Gap-free construction eliminates direct paths for sound through the barrier.
Barrier height: Sound barriers create an acoustic shadow in which the free flow of sound waves is blocked. Higher fences change the direction of sound by the greatest angle and increase the size of the &#;shadow zone&#;.
Distance between noise source and receiver: A certain amount of noise is diffracted by acoustic barriers, most audible to anyone standing in such a way that the barrier is an equal distance between them and the noise source. To avoid the effects of this diffraction, acoustic barriers should be built as close as possible to either the noise source or those being protected from the noise.
Relative height of source and receiver with respect to barrier: Ultimately, taller walls reflect and absorb sound better. It&#;s also important to consider the height of the noise source; the lower a source sits, the greater the angle of reflection will be, increasing the shadow zone.
Acoustic fencing doesn&#;t have any special planning permission requirements except those that apply to regular fences. For example, if a fence will be over one metre high and next to a highway or footpath next to a highway, or if it will be over two metres high, regardless of location, you need to apply for planning permission. No matter the height of your fence, it is always best to consult the local authority before installation.
Find out more about our acoustic barriers.
Questions and Answers about Noise
Federico Miyara
It's Sunday afternoon and you remember that at School you've been asked to prepare material about noise. Or perhaps a friend told you that nobody can sleep when his neighbour, a freshman at the local college, stays awake until very late in the night listening to music at full volume. Or somebody told you that noise is harmful and you want to know Whether it's true or not. Or you are just curious about everything--noise included.
Whatever the case, very likely you'll have a lot of doubts and will need some help. That's why we've prepared the following list of questions and answers.
Q1. What's noise?
A: It's any sound which interferes with our activities, conversations or rest. A given sound may be music or amusement for one person and noise for another one.
Q2. A sound has to be very loud to be considered as noise?
A: Not necessarily. Sometimes a very weak noise, such as a leaking tap, may distract us terribly. But louder noises are much more hazardous.
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Q3. What's noise made of?
A: As it happens with any sound, noise is the result of air vibration.
Q4. Does noise affect only humans?
A: Not at all. Noise does affect also animals and plants. The noise from helicopters flying over the Catarata Falls (at the North East of Argentina) for touristic reasons, for instance, has foced several animal species to migrate, altering severely the ecological balance of a wide area.
Q5. Can noise cause damage to buildings?
A: Perhaps, if it is extremely loud. However, most likely such damage will be the result of strong vibrations caused by the same device which produces the noise. For instance, heavy machinery operating at a factory might cause cracks on the neihbouring walls.
Q6. May I go deaf because of noise?
A: Extremely loud noises, such as an explosion close to your ears, may injury your ears forever. But even noises that aren't that loud, if listened to for several hours a day, may cause deafness after several years.
Q7. What noises are the most hazardous ones for my ears?
A: High-pitched noises are more dangerous that low-pitched ones. Noises that are short but very loud, such as those from impacts, blows with a hammer or explosions are particularly hazardous.
Q8. How loud must be a noise in order to be hazardous?
A: Any noise which makes it impossible to talk with a person who is close to you is dangerous, and so is a noise causing your ears hurt or ring.
Q9. Besides the effects of noise on hearing, are there any other effects?
A: Yes: it raises blood pressure and causes heart diseases, it stimulates violence, causes stress and lowers concentration.
In the case of children, it affects growth and interferes with learning.
Q10. What part of the ear is affected the worst by noise?
A: First let's say that the ear is actually made up of three parts: the outer ear (the pinna and the ear canal), the middle ear (the eardrum and three tiny bones called hammer, anvil and stapes) and the inner ear. The latter is a snail-shaped cavity in the bone containing a lot of amazingly small cells called hair cells (one millimeter contains about 500 of such cells). These cells are a sort of tiny microphones, and without them hearing would be impossible. It is their small size what makes them so vulnerable. Repeated exposure to loud noises gradually destroys them.
Q11. Is it possible to recover from noise-induced hearing loss?
A: Most unfortunately, the answer is no. The hair cells inside the inner ear, once destroyed, won't regenerate. That's why you should always take care of them.
Q12. Then, how come we recover from temporary deafness caused by a cold?
A: That's because then the middle ear gets filled with mucus, preventing the sound passage through it towards the inner ear. Once you recover from the cold, the mucus gets out from there and you can hear well again. As you can see, there is no destruction of hair cells.
Q13. Is it possible to become noise-addicted?
A: Many specialists say yes. That's another reason to avoid exposure to an excess of noise.
Q14. What are the main causes of urban noise?
A: One of the prime causes of noise is traffic flow: cars, trucks, buses, motorcycles (particularly those with defective silencers, or with no silencer at all). In the cities with an airport close to them or inside their limits, aircraft noise is quite a serious problem.
Other causes are the shops and factories which fail to comply with noise regulations, as well as discotheques, stadiums, shows oudoors, etc.
Q15. What can be done to abate noise?
A: It depends on the kind of noise. If it is a noise whose production is banned by any regulation (like a loud noise from your neighbour's house), you might call the police and ask that the law is enforced (most frequently it is not as simple as it sounds). Other kinds of noise may only be reduced resorting to preventative action. For instance, with public campaigns in order to educate drivers in driving quietly, avoiding the unnecessary use of the horn, and accelerating only in order to speed up and not for calling the attention of other drivers.
Q16. What can we, children, do to improve overall quietness?
A: The best thing you can do is to learn why the noise is not a good trade, and to add to your habits those of "sound hygiene". When you become grown-ups and be in charge of Planet Earth, you won't make the same mistakes as we make today.
Q17. What is "sound hygiene"?
A: It is a series of individual and social attitudes which everyone should have to avoid the hazards of noise and, at the same time, to care for the sound environment making our Planet a more friendly place to live in. Please, get more information by clicking here.
Q18. What do you mean by sound environment?
A: It's all the sounds arriving at our ears at a given location and time.
Q19. Which are the regulations on noise?
A: Quite a question! (or "quiet" a question?) Depending on where you live, you may find federal, state (or provincial) and local regulations. Federal regulations tend to be more general, stating principles and overall policies, and local ordinances, on the other hand, are more specific, often dealing with situations which have proven to be problematic. You may get information at the offices of those governmental agencies dealing with the environment or with health care. You may find some useful (though rather technical) information clicking here.
Q20. I've been told that in order to insulate noise coming through a wall I should cover it with carpet. Is it true? A: No. In order to insulate sound you need heavy materials, such as a thick brick wall, or else double gypsum board walls with the air space in between filled up with glass fiber. This subject is quite technical, but I wished at least to warn you that carpets, styropor or other light materials aren't good sound insulators.
Q21. Where can I find more information on noise?
A: If you go back to the home page, You'll find some links which will open the doors of virtually all Internet sites on noise. Even if many of them are aimed at adults, if you are so intelligent to be at this stage, you'll surely find lots of useful information. Good luck!
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