An acoustical barrier is a type of fence designed to reduce environmental noise from a particular source, such as a motorway or construction site. An acoustic barrier is made from a mix of high mass and insulative materials which are essential for effective soundproofing. The high mass will reflect sound away and the insulation will absorb sound that tries to travel through the acoustic barrier.

Can acoustical barriers be used on construction sites?

Yes, acoustic barriers should be used on noisy construction sites to mitigate the noise pollution to the surrounding area and to comply with regulations set out in the ‘Control of Noise at Work Regulations 2005‘ and the 1975 ‘Control of Pollution Act’. An acoustical barrier, or sound barrier, is not only for the protection of the surrounding environment, but also for the workers on site.

The table below, from the HSE, shows the upper exposure dB advised for various construction site activities. If noise is likely to exceed these figures, construction site managers must take action. One of the advisory steps is to install a noise barrier to reduce the reflection of noise on site as reflected noise increases exposure. The acoustic barrier will also prevent the travel of sound outside the site at dangerous levels.

Using an acoustic barrier to reduce road/traffic noise

It’s not uncommon to build effective noise barriers directly beside busy roads and motorways. The combination of a vehicle moving through the air, tyers in contact with the road, and engines roaring all accumulate to loud levels of noise.

For an acoustical barrier to work well against traffic, the height and location of the noise barrier is crucial. The acoustic barrier must be tall enough that the source of noise, (vehicles), can no longer be seen. This must also include the tops of lorries, so noise barriers should be the correct height to be fully effective.

Secondly, the soundproofing barrier should be placed as close to the source of the noise as is possible. This ensures that as much sound as possible is ‘captured’ and controlled before traveling too far.

The image below shows how sound from a motorway travels after an acoustic barrier is built. The sound will diffract around the top of the acoustic barrier, meaning that the closer you are to the barrier, the more effective it is. The picture clearly illustrates the importance of the height and distance from the source of the noise.

Noistop Reduction Estimate

Traditional acoustic barrier vs Noistop acoustic fence

A standard acoustical barrier usually comprises of one material like wood or concrete. While these materials have soundproofing qualities, they cannot both insulate against and absorb sound to maximum effect, as one material cannot encompass these two qualities sufficiently.

While a concrete acoustic barrier has a high mass and is a great reflector of noise, it is not effective at absorbing sound. With such a high reflection of sound, but low absorption, it can appear to amplify noises as they bounce around an area.

Likewise, a wood or timber barrier is also an effective insulator against sound, by reflecting it, but the ability for timber to absorb sound is quite low.

The Noistop sound barrier, on the other hand, takes both of the crucial soundproofing elements and puts them together into one acoustic barrier. The high mass of the galvanised steel with the highly absorbent mineral wool insulation, couple to create a fence that is able to at once reflect sound away and absorb sound which manages to enter the cavity of the fence. This makes the Noistop doubly effective as a soundproofing barrier solution to motorways and construction sites and improves the environment drastically.

What decibel reduction does an acoustical barrier have?

The decibel (measure of sound), reduction from an acoustical barrier can be difficult to accurately measure. Under lab settings, the soundproofing barriers are much easier to test and the whole environment is controlled. On site, in the field, the results are harder to measure as the levels are sound are in constant flux, however, Noistop acoustic barrier achieves the following results.

Noistop acoustic barrier achieves a laboratory measurement of Rw = 22dB for sound insulation. This means that the Noistop barrier can reduce sound transmission between two spaces by up to 22dB. The dense mineral wool within the fence has a sound absorption coefficient of 0.9, leading to a further reduction in noise passing through the fence.

When you consider that the human ear perceives a 10dB reduction as the halving of a sound, the performance of the Noistop acoustic barrier is incredibly effective. It’s strength lies in the coupling of the high mass and high absorption materials which ‘catch’ as much sound as possible and effectively manage noise levels.

Acoustical barrier installers

Permanent acoustical barrier options.

For a permanent acoustic barrier, there are several options. As we have already discussed, for a soundproofing barrier to be truly effective, it requires a mix of high mass and absorbent materials. Most permanent acoustical barriers for motorways are constructed from concrete and some from timber.

As we have already seen, timber is good at reflecting noise but not very good at absorbing it. For acoustic barriers by roadsides, the maintenance of the barrier also needs to be considered. Timber acoustic barriers require more maintenance than other options to ensure the structural integrity over its lifetime. Some timber acoustic barriers do offer a lifetime guarantee of 25 years, and a timber acoustic barrier is also a good option for aesthetically pleasing finishes.

Concrete acoustic barriers, on the other hand, are often chosen for their lasting durability with some claiming a 60 year service. Maintenance is also very low with only an annual inspection needed for some options. Concrete soundproofing barriers have a low absorption coefficient of around 0.1 – 0.2, (source), which means that the surrounding areas are fairly well protected by sound being reflected back to the motorway, however, the motorway itself becomes even louder. Concrete may also not be the best acoustic barrier choice if the finish needs to be sympathetic to the surrounding area.

Here at iKoustic, we use the Noistop acoustic barrier as it sits between the pleasing exterior of timber and the low maintenance of concrete solutions offering a blend of the two, and, most importantly, improved all around performance. The Noistop barrier will reflect sound back to the motorway, or industrial site, but also absorb sound to manage levels of noise more effectively. The Noistop barrier is highly modular, meaning it can be easily customised to the correct height and layout for your area.

When it comes to the look of the acoustic barrier, Noistop address this issue, too. There are a range of finishes, from galvanised or powder coated steel which protects the structure and ensures that maintenance is low, to cladding. Wood cladding over the acoustic barrier transforms the way it looks and allows it to easily fit into smart residential areas or to lift the look of industrial sites. The surface is also perfect for encouraging climbing plants over the barrier and turning this into a living, permanent green wall. The insulation material, mineral wool, is resistant to water and mold, meaning that there are no concerns of rot from within the fence.

Where are acoustical barriers commonly used?

Acoustical barriers are commonly used in areas of high noise where levels produced negatively impact on the surrounding environment and people.

In the UK, there are guidelines around the levels of noise that are acceptable form transport routes and industry. As already discussed in this blog, the guidelines reccomend using an acoustical barrier to combat levels of noise which exceed the upper exposure limits for various activities.

Acoustic barriers can also be used as an effective solution to noisy neighbors or properties close to roads and areas of high activity. This can totally transform a garden from noisy and stressful to peaceful and usable again. For more information about the residential uses of acoustic barriers and regulations applicable to domestic fences, see our other blog post here.

Do acoustical barriers work?

Yes. Acoustical barriers work well to reduces the levels of noise emitting from roads, construction sites and other areas of activity, down to acceptable levels. The combination of a high mass material and an absorbent material, work in harmony to ‘push’ sound away from an area and absorb sound to prevent it bouncing from surface to surface.

Acoustic barriers work on construction sites by enclosing the area of activity and thus reducing the amount of sound that pollutes the surrounding environment. For the acoustic barrier to work properly, it is best to choose an acoustic barrier that is also absorbent. This is very important as it prevents sound bouncing from surface to surface within the construction site, which would amplify the noise further and be harmful to workers. The Noistop fence is a great example of a barrier that can achieve effective noise reduction for construction sites.

Acoustical barriers also work beside motorways and busy roads. These barriers, when installed at the correct height and distance, will greatly reduce the transmission of sound from the vehicles to surrounding areas. You will often see concrete or timber acoustic barriers beside motorways which are great at reflecting noise back to the road and away from surrounding areas. However, this increases the level of noise on the road, by bouncing the sound back and forth. The Noistop will reflect sound away from the wider environment but also provides absorption to dampen the noise on the road, too.

How tall can you build acoustic barriers?

Good acoustic barriers, like Noistop, can be built up to 3 meters high, which provides excellent versatility between projects and ensures a good level of soundproofing. It’s always worth check your local council guidelines if you are looking to install an acoustic barrier. In general, barriers surrounding areas like motorways are decided upon after a noise assessment has been done. Various factors, such as the proximity to residential areas, size of the road and cost-effectiveness of the measures, will be taken into account.

The height of an acoustic barrier around UK construction sites is generally between 2 and 3 meters tall. This is subject to local authorities and the actual height may vary depending on the specific requirements of the construction site and how these affect the local area and workers.

Who can install acoustical barriers?

Anyone can install an acoustic barrier, (providing you have the planning permission, if required, and permission to use the land). However, there are several things to consider before installing a soundproofing barrier by yourself.

Acoustic barriers have high mass, (to be effective), making them heavy to lift and shift. You should consider site access, risk to yourself, or others, installing them, and optimum conditions. When this has been done, you should have an idea of the number of people required to safely install the acoustic barrier on your site.

Noistop acoustic barrier panels are erected in much the same way as a garden fence, with posts and panels to slot in. To ensure the acoustic barrier is totally effective, an acoustic seal is taped between the panels to prevent sound ‘leaking’ through.

For more information on safe and correct installation, see the installation guide below.