Tag: noise environments

Categories
Building Accoustics

Researchers Develop ‘Acoustic Metamaterial’

Boston University researchers, Xin Zhang, a professor at the College of Engineering, and Reza Ghaffarivardavagh, a Ph.D. student in the Department of Mechanical Engineering, released a paper in Physical Review B demonstrating it’s possible to silence noise using an open, ring-like structure, created to mathematically perfect specifications, for cutting out sounds while maintaining airflow.

They calculated the dimensions and specifications that the metamaterial would need to have in order to interfere with the transmitted sound waves, preventing sound—but not air—from being radiated through the open structure. The basic premise is that the metamaterial needs to be shaped in such a way that it sends incoming sounds back to where they came from, they say.

As a test case, they decided to create a structure that could silence sound from a loudspeaker. Based on their calculations, they modeled the physical dimensions that would most effectively silence noises. Bringing those models to life, they used 3-D printing to materialize an open, noise-canceling structure made of plastic.

Trying it out in the lab, the researchers sealed the loudspeaker into one end of a PVC pipe. On the other end, the tailor-made acoustic metamaterial was fastened into the opening. With the hit of the play button, the experimental loudspeaker set-up came oh-so-quietly to life in the lab. Standing in the room, based on your sense of hearing alone, you’d never know that the loudspeaker was blasting an irritatingly high-pitched note. If, however, you peered into the PVC pipe, you would see the loudspeaker’s subwoofers thrumming away.

The metamaterial, ringing around the internal perimeter of the pipe’s mouth, worked like a mute button incarnate until the moment when Ghaffarivardavagh reached down and pulled it free. The lab suddenly echoed with the screeching of the loudspeaker’s tune.

How acoustic metamaterial works – Geonoise Instruments
How acoustic metamaterial works – Geonoise Instruments

Now that their prototype has proved so effective, the researchers have some big ideas about how their acoustic-silencing metamaterial could go to work making the real world quieter.

Closer to home—or the office—fans and HVAC systems could benefit from acoustic metamaterials that render them silent yet still enable hot or cold air to be circulated unencumbered throughout a building.

Ghaffarivardavagh and Zhang also point to the unsightliness of the sound barriers used today to reduce noise pollution from traffic and see room for an aesthetic upgrade. “Our structure is super lightweight, open, and beautiful. Each piece could be used as a tile or brick to scale up and build a sound-canceling, permeable wall,” they say.

The shape of acoustic-silencing metamaterials, based on their method, is also completely customizable, Ghaffarivardavagh says. The outer part doesn’t need to be a round ring shape in order to function.

“We can design the outer shape as a cube or hexagon, anything really,” he says. “When we want to create a wall, we will go to a hexagonal shape” that can fit together like an open-air honeycomb structure.

Such walls could help contain many types of noises. Even those from the intense vibrations of an MRI machine, Zhang says.

According to Stephan Anderson, a professor of radiology at BU School of Medicine and a coauthor of the study, the acoustic metamaterial could potentially be scaled “to fit inside the central bore of an MRI machine,” shielding patients from the sound during the imaging process.

Zhang says the possibilities are endless, since the noise mitigation method can be customized to suit nearly any environment: “The idea is that we can now mathematically design an object that can block the sounds of anything”.

Source:

https://phys.org/news/2019-03-acoustic-metamaterial-cancels.html

Categories
Asia Noise News Building Accoustics

Noise and Vibration Monitoring for Construction Sites

In a densely populated city like Bangkok, most of the construction projects are surrounded by condominiums, offices or residential areas. The construction sites must control the noise and vibration that may affect the surroundings. Construction sites need to control the noise and vibration levels that they produce following the EIA standard.

To manage this, noise and vibration instruments are installed which automatically will send alarms to the construction company if the thresholds are exceeded.

Noise Monitoring Station

Sound level meter class 2 according to IEC61672-1 standard which can collect the data of SPL, LEQ and LMAX. These instruments are calibrated before they are installed at a construction site. The system has a LED display and warning light when noise levels in the site are over a trigger level, which is referred to in the standards for maximum sound levels around construction sites.

According to the announcement of National Environment Board no.15 BE.2540 (1997) in the topic of “Standard loudness”, the average sound 24 hour must not exceed 70 dBA and the maximum peak level must not exceed 115 dBA.

Sound level meter are designed to be used outdoors and an additional LED display was added by Geonoise which is a professional sound and vibration company. Sound level meter with LED display also can analyse the loudness in percentile (Statistical,Ln) or analyse the frequencies in 1/1 and 1/3 octave bands. In addition to storing vibration data, you can also create level notifications in Alarm Alert format before vibration levels exceed the standard value for monitoring the activities being performed.

Vibration Monitoring

In the construction industry, transportation Industry and most large industries vibrations will occur.
High vibration levels will cause structural damage to buildings, bridges, structures as well as nuisance or health risks to occupants in exposed (residential) buildings.

Therefore, it is necessary to comply with the standard of vibration in a building according to the Announcement of the National Environment Board Announcement No. 37, BE 2553 (2010) Re: Determination of Standard Vibration to Prevent Impact on Buildings and the measuring instruments need to comply with DIN45699-1.

At construction projects in Bangkok, most cause a lot of unwanted noise and vibrations. Vibration caused by construction projects are caused by piling work as well as the increased traffic of large trucks that enter and exit the construction site. To prevent that vibration levels will be exceeded, a vibration monitoring system will have to be installed.

The Announcement of the National Environment Board No. 37, BE 2553 Vibration standards to prevent impacts on buildings is the main regulation to comply with for construction sites in Thailand. The vibration standards are derived from DIN 4150-3 whereas buildings are classified into 3 types.

Building types according to DIN 4150-3:

  • Type 1 buildings such as commercial buildings, public buildings, large buildings, etc.
  • Type 2 buildings such as residential buildings, dormitories, hospitals, educational institutions, etc.
  • Type 3 buildings, such as archaeological sites or buildings that cultural values but not strong, etc.

In addition to storing vibration data, you can also create level notifications in Alarm Alert format before vibration level exceed the standard value for monitoring the activities being performed.

Categories
Asia Noise News Building Accoustics

Feeling Unproductive? You Might be Overlooking This Productivity Killer

Feeling Unproductive in Office - Geonoise Instruments

Feeling Unproductive in Office – Geonoise Instruments

We believe that the best way to be highly productive is to be able to get into our monoideal state. Josh Kaufman says in his book “The Personal MBA”:

“Monoidealism is the state of focusing your energy and attention only on one thing. It’s often called a “flow” state: clear, focused attention on one subject for a long period of time.”

For this to happen, potential distractions and interruptions need to be eliminated. This is the reason for some people, working early in the morning or late at night can feel very productive – because on a normal day, no one is going to call you at 4 in the morning.

However, most of us do our work in an office which does not operate at those silent, undistracted hours. The good news is, we still can manage our potential distractions by knowing what distracts us the most. This can be done by allocating a time when you want to be in your monoideal state and free yourself from distractions during that time. For example, you can put your phone into flight mode and turning off email notifications from 8 to 11 and start to check emails and communicating with the outside world from 11 until lunch. The timing will depend a lot on the type of work you are doing and how much time will you need to be in monoideal state.

Unfortunately, there are things that is out of your locus of control – there is a retrofitting job upstairs, your co-worker decided to sing along to the song he is listening to, people in the other room are laughing loudly (are they talking about their boss?) and so on. If it’s not in front of your eyes, for example pop-up notifications on your screen, most of the distractions come to you in a form of sound, or I think it’s better to call it “noise”.

Noise is a productivity killer that you might be overlooking, especially if you have passed the stage of being distracted by your phone, browsing Facebook on your computer and looking at cat videos on Youtube. Fortunately, noise is manageable in a few different ways. The most viable option for an existing office is to make noise-related rules and to make everybody aware that noise can reduce their productivity. For example, companies can make rules that retrofitting job, singing and gossiping must be done outside of office hour. Another way to fix this is to separate areas for people who want to be focused and areas where people can socialize and discuss with their co-workers.

The best way to manage noise? Is to take noise into consideration from the beginning of the design process of the working space. This can be a long and complex process where there are a lot of aspects to be considered in designing an ideal office. It needs a balance between visual pleasure, company’s philosophy, functionality, health, safety and all other aspects that we want to take into account. A lot of times, all those aspects will relate to noise or acoustics in some ways, depending on each unique case.

For us acousticians, these are the things that we typically think about when helping others to design their working space (and actually any other built environment):

  • Ambient noise: We want the noise level inside of the working space to be reasonably low, whether it is intrusion from outside such as traffic, railway, aircraft and neighbouring building (neighbour’s mechanical system can be quite noisy), or the noise from inside the building such as HVAC system and lifts.
  • Sound insulation: We don’t want to hear sound that we don’t want to hear from the next room, upstairs or downstairs. By designing a suitable ceiling, flooring and wall systems, a sufficient sound insulation can be achieved.
  • Room acoustics: We want to be able to listen comfortably and understand verbal information that we want to. This is critical especially in meeting rooms and event space.
  • Sound reinforcement and public address system: We want the sound reinforcement and public address system to be heard clearly while not disturbing others who don’t want to hear it.

All the above can also be done after the building and the working space is built. But if it’s done before it’s built, you will have a lot more options and be more cost efficient rather than changing what is already been built.

So, if you are a highly productive person, or if you want to become one, we would suggest you to consider noise in choosing the space you are working in.

Categories
Asia Noise News Building Accoustics

Are You Stressed at Work?

Are you stressed at work?

How many times did you need to cover your ears at work? You might be stressed because you are working in a noisy environment even without realizing it.

A noisy environment is one of the primary stress triggers for the employee and it will lead to a reduction in productivity. It is dangerous for your health but it could also impact your bonus at the end of the year? Let us remind you how noisy your working environment is by mentioning some sources:

  • Copy machines
  • Obnoxious ringtone
  • Computers
  • Air Conditioning
  • Noises from outside the office buildings (Trucks, Airplanes, Highway noise, nearby constructions)
  • Laughing/Talking
  • Gossip about boss
  • Gossip about co-worker who is not invited into WhatsApp Group

Those are common noise sources that might be contributing to the noise around you. We must remember that the distinction between noise and sound is very subjective. It can be particular to each person and even depend the situation.

Noise and sound can both be dangerous for your health and can be easily measured to quantify. The graphic below shows some noise levels. Fifty decibel would be great for a working environment, exposure for long time to noise levels above 80 decibel will permanently damage your hearing.

 

How Loud is Too Loud? – Geonoise Instruments

 

After reading the graphic, please take a moment to think about how many decibels your ears have to endure daily? Let’s say that you’re working in a general business noisy office. The noise levels can be reaching up to 90 decibels because of the cumulation of various noises such as laughter, yelling, ringtones, etc. The World Health Organization (WHO) claims that exposure to noise causes stress, anxiety, depression, high blood pressure, and heart disease. Furthermore, loud sounds will damage sensitive structures of the inner ear and cause noise-induced hearing loss (NIHL).

The damage because of the noise exposure is gradual; you might not notice the signs or you ignore them until they become more apparent. Here are the symptoms of the Noise-induced Hearing Loss:

  • Sounds have become distorted or muffled
  • You can hear people, but you can’t quite understand what they’re saying
  • You can’t hear or understand speech from 3 feet away or farther
  • You must turn the volume up more than others do in order to hear it as well as they can

All checked?

Please call professional help immediately! If it is not, congratulations, you still have a good hearing. But it doesn’t guarantee you that you will be free from NIHL.

Here are the tips on how to stay sane in a noisy working environment and prevent the NIHL at the same time:

•   Bring earplugs to your work!

You only need to spend a few thousand rupiahs for this. Wearing earplugs can help you to reduce the noise by 18 – 34 decibels. It depends on the models/brand. By blocking/reducing that amount of noise, you’re still able to hear the sound around you.

•   You might want to try the Noise Cancelling Headphones

It is made for keeping the noise away from your ears. If you use this in the office, it not only will help you block the annoying noise but also will make your music sounds way better than any other headphones in the same situation. The price ranges between a hundred thousand rupiah – millions of rupiah. It is an excellent investment, though!

•   Take a break!

When the noise around you is too much to handle, give your ears a break! It gives your eara time to recover from the stressful sound and this action also a preventive way to the damage of your ears. None of them seems to be working for you? Please contact the acoustical consulting service. They will help you to find the best solutions to your problems.