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Asia Noise News

Coronavirus Lockdown Gives Animals A Rare Break from Noise Pollution

The COVID-19 lockdown could become an unprecedented natural experiment in noise pollution. Some of the world’s most vocal animals — birds and whales — might already be benefiting from a quieter environment.

While a drop in transportation during the coronavirus lockdowns has led to lower pollution levels across the world, the slowdown in traffic has also lowered another big polluter: noise.

According to the World Health Organization (WHO), noise pollution affects over 100 million people across Europe and, in Western Europe alone, road traffic accounts for premature deaths equivalent to the loss of roughly “1.6 million healthy years of life.” 

Take the disturbance to human health out of the equation, and noise remains a big source of pollution for the other inhabitants of the planet as well, namely, animals. 

But how much have animals in countries on lockdown really benefited from the drop in noise levels? Turns out, that’s a very difficult question to answer.

Birds will benefit the most

Birds — by far the most visible animals found in cities, and the most vocal — stand to be among the biggest beneficiaries of quieter streets and parks. 

The signals birds send each other through song is a means of survival. Without the ability to sing, hear and be heard, birds would have a difficult time finding a mate or defending their territory from predators.  

There are reports of seeing more birds during the lockdown. Ornithologists say this is due to increased awareness of people’s surroundings while at home

Human activity influences bird behavior, even prompting them to communicate at less ‘busy’ times of day

The swift rise of human-made noise — also known as anthropogenic noise — over the past century has made this harder for birds. 

Just like humans who have to speak up in a loud setting, birds, too, have to sing louder to communicate properly in today’s noisy world, according to ornithologist Henrik Brumm, who heads the research group for the communication and social behavior of birds at the Max Planck Institute for Ornithology near Munich.

“This happens really fast,” Brumm told DW. “We found out that it takes roughly 300 milliseconds, so less than 1 second, for birds to readjust when the level of noise rises. So, when their surroundings become louder, they sing louder, too.”

Are birds getting quieter? Maybe.

Birds are already known to sing more quietly in the early morning hours of the weekends, says Brumm. The reason: there’s less traffic to compete with. 

With Europe on lockdown, Germany for its part, has seen passenger air travel slashed by over 90%. Moreover, car traffic has dropped by more than 50% and trains are running at less 25% their usual rates.

A recent study from the Max Planck Institute also suggests that chronic traffic noise can have a negative effect on embryo mortality and growth in zebra finches. This, in turn, could mean that the current lockdowns coinciding with mating season could lead to not only more, but also healthier hatchlings. That is, as long as their parents choose a spot that’s still safe from humans after the lockdown ends.

Though it’s difficult to speculate without real-time data, Brumm says, it stands to reason that the current period of quiet could mean birds might be singing more softly than usual, which would already be a huge benefit.

At land or sea, noise is bad news for animals

Birds aren’t the only animals that stand to benefit from less noise. According to a recent study published in the journal Biology Letters, noise pollution affects any number of creatures ranging from frogs, to shrimp, to fish, mammals, mussels and snakes.

In fact, another habitat garnering more and more attention for noise pollution is the ocean. As bioacoustics expert Christopher Clark described it in with Yale’s environmental magazine, the din from oil and gas activity, for example, is filling entire ocean basins with “one big storm of noise.”

While research on noise pollution and marine life, just like with ornithology, is in its early stages, a landmark study conducted in the days after 9/11 found that less shipping traffic seemed to make whales calmer.

Examining the feces of right whales — a species of baleen whale that can reach 15 meters in length and weigh up to 70 tons — researchers found that fewer ships in the waters along the US-Canadian coast correlated with lower stress hormones.

The noise levels from shipping traffic, whose 20–200 Hz hum disturbs sea life despite being a low frequency, decreased by 6 decibels, with a significant reduction below 150Hz .

An unprecedented time for researchers

Just like ornithologists, marine life researchers have also found correlations between noise and interruptions in behaviors like foraging and mating. Whales, like birds, also “mask.” That is to say, they sing louder to be heard over noise disturbances, be they high or low frequency sounds.

“It’s really a huge footprint that these activities have in the ocean,” according to Nathan Merchant, an expert on noise and bioacoustics at the UK’s Centre for Environment, Fisheries and Aquaculture Science (CEFAS).

Source: https://www.dw.com/

And the sources of noise pollution — ranging from shipping, to wind farms, to the sequence of powerful blasts from seismic air gun tests used to locate oil and gas deposits in the ocean deep — are even harder to escape in the ocean than on land.

“It has a lot to do with how sound travels under water. Sound can travel much further and much faster than in air,” Merchant told DW.

Instruments off the coast of North America, for example, can detect seismic air gun testing as far away as the Brazilian coast.

With many cruises suspended, oil freighter traffic impacted by an oil price crash and rig activity being run by skeleton crews to curb the spread of COVID-19, marine biologists could potentially find a treasure trove of data once they’re allowed to go back into the field. 

“We have underwater noise recorders at sea as we speak, but they aren’t cabled to land. So, we’ll find out when get out on a ship in several months’ time and get the data back,” Merchant said. 

The more interesting question by that point might be how marine life responds to a sudden reintroduction of the human cacophony after an unexpected period of rest.

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Asia Noise News

Noise, Nuisance or Danger

As an introduction to this question some basic facts about noise.

Basic noise facts

Noise is typically defined as ‘unwanted sound’. The unit for sound is the Decibel which is a value calculated with logarithms from the pressure to get a scale from 0 to 120 dB where 0 dB is the hearing threshold for a young person with healthy hearing and 120 dB is the pain threshold.

We can state that noise is a type of energy created by vibrations. When an object vibrates it causes moment in air particles. The particles will bump into each other and will generate sound waves, they are ongoing until they run out of energy.

High and low tones are perceived by our hearing due to fast and slow vibrations.

Sound needs a medium to travel and the speed of sound is around 340 meter per second. Examples of typical noise levels:

Due to the nature of the calculation of Decibels we cannot just add them together.

Examples:

3 dB + 3 dB = 6 dB

But…..

10 dB + 10 dB is not 20 dB but 13 dB

The Decibel (sound pressure level) for sound in air is relative to 20 micro pascals (μPa) = 2×10−5 Pa, the quietest sound a human can hear.

The human hearing system

The human hearing system is capable of hearing sounds between 20 Hz and 20000 Hz. Below 20 Hz is called infra sound and above 20000 Hz is called ultrasounds. Both infra- and ultrasound is not audible for us. Elephants however can hear frequencies as low as 14 Hz and bats can hear frequencies up to 80000 Hz.

A special noise weighting for the human perception has been introduced in the 1930’s and called the A-weighted Decibel, dB(A). This was introduced to align the noise levels with the sensitivity and physical shape of the human hearing system.

Basic human hearing system

When sound waves enter the ear, they travel up the ear canal and hit the ear drum, the ear drum will vibrate and the three smallest bones in the human body will transfer these vibrations to the fluid in our inner ear’s sensory organ the cochlea. The sensory hair cells will vibrate which will send nerve impulses to the brain, the brain will translate these impulses for us and we perceive sound!

Dangers of noise

Noise from certain music can be a very pleasurable sound for one person and a horrific noise for another. From this fact we can see that noise is not only an absolute value but also strongly depending on the receiver’s mindset.

However, there are some clear absolute values concerning the danger levels of noise.

  • Generally accepted as safe is spending 8 hours per day in an environment not exceeding 80 dB(A)
  • NOT safe would be to spend 1 hour in a disco with levels at 100 dB(A) which are easily exceed nowadays

Apart from the obvious hearing loss there are many other issues that can arise from exposure to (too) high noise levels such as:

  • Hypertension
  • Heart disease
  • Annoyance – stress
  • Immune system – psychosomatic

The positive side to remember is that Noise Induced hearing loss is 100% preventable!!

Worldwide solutions

Governments (especially in Europe) know the actual cost of high noise exposure and they concluded that protecting their citizens from high noise exposure (during working hours, recreation as well as during sleep) is far more effective than dealing with the costs of citizens enduring high noise related illnesses, demotivation, sleep disturbance etc.

They are investing in quiet schools (optimal learning environment), quiet hospitals (patients recover a lot faster in quiet wards), implement city planning to create quite zones.

Of course, they also have strong noise regulations that are being enforced.

Acoustical societies worldwide help to create awareness and leverage noise legislations with governments.

Noise in Asia

I have been living in Asia for the last 15 years and of course I noticed it’s noisy. Noise regulations (if exist at all) are very lenient and mostly not enforced. I’m very happy to see that Acoustical Societies are coming up in Asian countries and can convince governments to invest in setting up proper noise regulations and enforcing them. I’m very happy to be able to contribute to a quieter world by creating more awareness for the dangers of noise!

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

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.

Categories
Asia Noise News

Many ways to reduce urban noise in China

Many ways to reduce urban noise in China

According to a recent report issued by the Ministry of Environmental Protection, a quarter of Chinese cities exceeded the limits on noise pollution last year. Beijing News commented on Monday:

Chinese residents are no stranger to noise pollution, ranging from late-night construction to daytime traffic. They suffer from a variety of noises on a daily basis, but their complaints are often ignored or not dealt with properly.

Noise pollution, in effect, can be as harmfull as air, water and soil pollution, as it is a major cause of insomnia, even heart attacks.

There have been successful attempts to curb noise pollution in some countries. In Japan, construction sites are always surrounded with heavy shields to prevent noise and dust from spreading out. Germany has specific limits on road decibels and has applied noise reducing technology to its roads.

In comparison, China’s solutions to the noise problems, be they technological or legislative, still lag far behind. Neither the environmental protection authorities, who are supposed to take care of industrial noise, nor the police that should play a role in curbing traffic noise do their job properly. And public complaints about urban noise pollution often fall on deaf ears.

Building roadside shields should be a viable solution to traffic noise pollution. But they are poorly built even absent in many cities due to the lack of cooperation among departments. The noise pollution policies need to have more teeth to effectively tackle the problem.

Source: http://www.chinadaily.com/