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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
Asia Noise News

City noise pollution linked to hearing loss: study

Urban noise pollution and hearing loss are closely linked, according to rankings of 50 large cities in both categories released on Friday.

High-decibel urban areas — such as Guangzhou, New Delhi, Cairo and Istanbul — topped the list of cities where hearing was most degraded, researchers reported.

Likewise, cities least afflicted by noise pollution — including Zurich, Vienna, Oslo and Munich — registered the lowest levels of decline in hearing.

This statistical link does not necessarily mean the constant din of city life is the main driver of hearing loss, which can also be caused by infections, genetic disorders, premature birth, and even some medicines.

The findings are also preliminary, and have yet to be submitted for peer-reviewed publication.

“But this is a robust result,” said Henrik Matthies, managing director of Mimi Hearing Technologies, a German company that has amassed data on 200,000 people drawn from a hearing test administered via cell phones.

“The fact that noise pollution and hearing loss have such a tight correlation points to an intricate relationship,” he told AFP.

Researchers at Mimi and Charite University Hospital in Berlin explored the link by constructing two separate databases.

The first combined information from the World Health Organization (WHO) and Norwegian-based technology research group SINTEF to create a noise pollution ranking for cities around the world.

Stockholm, Seoul, Amsterdam and Stuttgart were also among the least likely to assault one’s ears, while Shanghai, Hong Kong and Barcelona came out as big noise makers.

Paris — one of the most densely populated major cities in Europe — scored as the third most cacophonous.

The ranking for hearing loss drew from Mimi’s phone-based test, in which respondents indicated age and sex. Geo-location technology pinpointed the cities.

‘Silent epidemic’

The results were measured against a standard for age-adjusted hearing.

On average, people in the loudest cities were ten years “older” — in terms of hearing loss — than those in the quietest cities, the study found.

Stacked side-by-side, the two city rankings are remarkably similar, suggesting more than an incidental link.

The findings highlight the need for better monitoring, the researchers said.

“While eye and sight checks are routine, ear and hearing exams are not,” said Manfred Gross, head of the department of Audiology and Phoniatrics at Charite University Hospital.

“The earlier hearing loss is detected, the better the chances are for preventing further damage.”

Collaborations between scientists and private companies that collect health-related information from consumers are becoming more common in the era of Big Data.

California-based DNA genetic testing company 23andMe, for example, has worked extensively with university researchers to ferret out rare genetic disorders by combing through mountains of anonymous data from its clients.

Also on Friday, World Hearing Day, the WHO released figures showing annual costs of unaddressed hearing loss of between US$750 billion and US$790 billion globally.

Direct health care costs were calculated to be up to US$107 billion, with loss of productivity due to unemployment or early retirement about the same.

“Societal costs” — stemming from social isolation, inability to communicate and stigma — were estimated at more than US$500 billion.

In a recent editorial, the medical journal The Lancet said hearing loss is a “silent epidemic,”noting that proper care remains out of reach for millions of people.

Mimi Hearing Technologies develops music applications that adjust to the individual hearing deficiencies of listeners.

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