Some would ask ‘How does the Noise Control Barrier work?’. That would be the first question one will have to ask to explore more about it. However, with minimal insights on it, some would make a mistake – thinking Noise Barriers are just like a medium to stop noise from escaping.
There are 2 known variables when it comes to the barriers’ effectiveness. Mostly used in the Noise Control Barrier industry, these two variables are the benchmark to label the particular barrier (wood, concrete, vegetation plot) as effective or otherwise.
NRC: Noise Reduction Co-efficiency – A *average* rating to determine how much sound an acoustic product can absorb.
STC: Unit of measurement of how much sound is stopped. Usually used to compare to products.
In an industry where innovation is encouraged, the Noise Control Barrier does evolve to other form from time to time. The two main types that we often hear about are the Permanent and the the Temporary. This two types represents the duration of how long the barriers will be there. For most, Permanent ones will be situated on site for more than 10 years and the Temporary ones offers at least 2 – 3 years noise mitigation solution until it is required by other sites for reuse.
The question has always been, how effective are these Noise Control Barriers. There has been reports and articles on how Noise Barriers are still hurting nearing dwellers and it was later deemed, ineffective. Read here for the article: (https://jinbiao.com.sg/why-is-noise-barrier-insufficient/)
How do we deemed it effective or otherwise?
Firstly, we touched on the ratings given to justify if the product is workable for our problem. This ratings are indeed produced from testing out products in lab and it goes through stringent subjects and methods to finalize with the result.
The other way is of course, to test. With the currently ongoing Quieter Construction Fund, companies whom went for the reimbursement scheme were required to hold a noise test upon installation. Test held by Hebei Jinbiao together with the client was witnessed by NEA officers along with a third party noise consultant. Though set up might vary with accordance to site availability, the procedure are held the same. View the process here: (How is a Noise Test done? – Noise Control Barrier)
The ratings we learned in the beginning part of the post are an important aspect to rate the effectiveness of the mitigation product and it should not be viewed lightly. These ratings, however, were adduced from stringent lab procedure following a global standard. Nonetheless, the ratings are formed from perfect lab test where there are one source and one receiver. On site, on the other hand, will take more than just erection of the noise mitigation as the solution.
There are a few criteria to meet when considering the erection of noise mitigation products. In some countries, the weightage of importance on its capability to stop sound (STC) is more. As such, one will always ask themselves these questions:
1) Why do some countries settle for concrete wall for noise mitigation solution? (compare Jinbiao Noise Control Barriers to Concrete Wall)
2) Why are products found in Singapore average on the STC but high in NRC?
3) Which variables should we look at, especially when I am in the midst of putting it in the tender specification.
4) Is this product better than the other because its STC is more?
5) Both product has the same STC but one is cheaper than the other. Which should I choose?
The science behind Noise Control Barrier
Yes, it is true some products do have better ratings, but does it really serve the actual purpose? Noise Control Barrier products differs from a normal hoarding because Noise Control Barrier has a variable which has the cutting edge. NRC.
“Any medium that is being used on site between the noise source and receiver will always be successful in mitigation SOME sound”
But the real question is, by how much? Does it reach a count that is considered impactful? When it ‘stops’ sound, where does this sound travel to (deflected sound)? Will it be more negative to focus on sound cutting only?
Noise Reduction Co-efficiency plays a huge role in noise mitigation. This variable when understood, would definitely change the perception of most and also would potentially change the minimum specification needed to tender for. Where the NRC is at its optimum (currently, Hebei Jinbiao has one of the highest at TNCB: 0.7 PNCB: 0.95) it not only deflects (as most does), it absorbs too. That is where the difference would be. The additional sound energy broken down would mean a drop in decibel and even if its by 2-3 decibel, to the human ear, it is impactful, effective and positive change compared to without any mitigation solution.
The information shared and suggestive ideas are mostly directed for the construction industry. To find out more about Noise Control Barriers, contact us at firstname.lastname@example.org or call in +65 6250 3385.