Noise Mitigation Becomes a Priority

In an interaction with Industry Outlook, Chintan Athalye, Director, ARK Noise Control – India and Director, Athalye Group shares his views on the evolution of industrial noise control market.  

With increasing industrialization and rising manufacturing output, the industrial noise control market is expected to grow at a rapid pace. How do you see the current evolution of the industrial noise control market? What are the major factors contributing to its growth?

The awareness of the industry for maintaining lower noise levels has significantly increased over the last decade. We have seen a significant rise in the number of enquiries received, for different types of machinery. This can be attributed to the government regulations all over the world becoming more stringent and enforceable by law. Now a days, most project owners choose to maintain the overall noise levels below 85 dBA for most of the machinery that they purchase and put it as a non-negotiable criterion in their project specifications.

A decade ago, this used to be a negotiable criterion and the noise mitigation treatment was generally avoided in order to reduce the overall cost of the project. Now this has significantly changed. More number of companies are opting to get certified according to OHSAS 18001, and are choosing to take care of their workforce when it comes to exposure to high noise levels every day at their work-environment. We expect the market size itself to grow by 20% year-on-year in the upcoming decade.

What are the major challenges in maintaining suitable noise level in a manufacturing environment? How can those challenges be addressed?

The major challenge is the awareness and understanding of the Project Owner (end customer) and their engineering team, about how sound works in a sound reflective field when there are multiple sources of noise in a particular room. This is primarily because ‘Acoustics’ is not a topic that is covered in the syllabus in Mechanical Engineering undergraduate degrees (B.E. / B.Tech) beyond 3 or 4 pages in the entire 4 years. Due to this, the understanding of acoustics for most project owners is very limited.

For example, if each individual equipment is ‘guaranteeing’ 85 dBA of Noise level in ‘Free Field Conditions’ and if there are 5 such equipment located in close proximity of one-another, then overall Noise Level measured inside that room (assuming brick walls on 4 sides, and Corrugated Roof sheets for ceiling) is likely to be in excess of 93~94 dBA. This increase is due to Noise Levels contributed by multiple sources getting added up logarithmically, and this noise level is amplified even further because of presence of sound-reflective surfaces in the room.

To solve this problem, some basic level of analysis needs to be conducted of “Overall” noise level in the shop-floor as a result of collective noise generation because of possibly hundreds of machinery together, and accordingly designing the Noise Mitigation treatment for each individual source of noise. In most projects, this problem is highlighted only after it has already occurred, i.e., all equipment are already installed, commissioned & running.

Absorption of low frequency sound in an effective manner is a challenge in noise control and architectural acoustics. How do you propose to solve this problem?

Low Frequency Sound Waves, i.e. for all frequencies below 250 Hz, the wavelength of the sound is large. Lower the frequency, larger is the wavelength for the sound at that frequency. For complete absorption of the sound ‘λ / 4’ of thickness of insulation is generally required. For lower frequencies, the provided insulation thickness is never even close to that mentioned above. As a result, the low-frequency sound generally comes out of the ‘Acoustic Enclosure/Acoustic Treatment’ either unattenuated or reduced merely by 3~4 dBA which is not sufficient for achieving an overall noise reduction beyond 20 dBA from the Acoustic Enclosure alone. ARK has developed ‘Multi-Absorptive’ Technology to provide higher noise reduction even for low-frequency sound.

As far as Architectural Acoustics is concerned, modal analysis for the room needs to be conducted in order to predict which frequencies would resonate for that particular size and shape of the room. Once this data is predicted, Bass Traps specifically designed for those target resonant frequencies need to be placed in the corners of the room in order to provide sufficient absorption to the resonating low frequencies, especially in larger rooms like Banquet Halls, Auditoriums etc. Without this, the ‘Clarity’ of sound played on the speakers in that room reduces drastically.

Industrial rooms made of brick/RCC walls are unable to prevent noise from escaping because of their reflective nature. What kind of acoustic treatment can be provided for such industrial rooms to achieve desired sound transmission loss?

For Industrial rooms made of brick walls which is mostly applicable for DG Set rooms / Engine Rooms or Compressor rooms, are purely reflective in nature for the sound. Mostly all such walls are made of at least 200mm thick layer of Bricks due to which these walls provide an inherent noise reduction rating of 25+ dBA because of the wall itself. However, these walls are only reflecting the sound back towards the room. The sound therefore, gets amplified (by even 10+ dBA sometimes) inside the room due to multiple reflections, and then gets out through the doors / cutouts / openings made on the walls / ceiling of that room.

Therefore, effective treatment of the Doors, and providing Silencers for all cutouts made on the room is very critical for achieving overall lower noise levels outside the room. Where the doors, cutouts and openings are properly designed for effective noise reduction of 20+ or 30+ dBA as per the requirement of the project, the walls can be treated even by acoustic Panels which are targeted to provide a better absorption coefficient for the surface of the acoustic panel. ARK Provides turnkey solutions for such requirements such as Acoustic Treatment for Engine Test Cells, DG Set Rooms, Engine Rooms or Compressor Houses.

Where do you see the industrial noise control market in the near future? Which new technologies is it going to adopt to become more innovative? What is the future road map for your company to gear up for emerging challenges in this domain?

In the coming decade, more number of companies, industries and governments will choose to protect their employees / citizens against the exposure to higher noise levels, due to the growing awareness. This is essential in preventing health-risks associated with high noise dosage such as permanent hearing damage, high blood pressure, headaches, etc. The challenge will be to be cost-competitive in this growing market and rising raw material prices. ARK Noise Control – India is scaling up its facility for the continuously increasing demand in terms of the capital resources as well as human resources. We are also working towards optimizing our manufacturing processes in order to deliver a better value to our customers located in 40+ countries across the world.