Right to Quiet Society Noiseletter
Fall 2014, page 3

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Noise pollution: Bring (relief from) the noise

By Daryl Worthington

You may not have heard, but 30 initiative was launched by the American Centre for Hearing and Communication in 1995 to raise awareness of the health problems caused by noise pollution. The events for the day don’t receive the same level of promotion as the likes of World Water Day or Earth Day, especially here in Europe, but the growing number of us living in urban areas means the issues of noise pollution shouldn’t be ignored. In the European Union, 110 million people are negatively affected by the noise from roads and motorways. The World Health Organisation estimates that about 40% of Europeans are subjected to traffic noise exceeding 55dB, and 30% are subjected to the same, even during the night. 20% of the continent’s population suffer from noise levels experts describe as unacceptable. For instance, exposure to Subway noise for just 15 minutes a day can lead to hearing loss over time. The European Noise Di­rective (END) was created in 2002 to investigate and manage environmental noise, and to provide guidelines to public authorities.

To coincide with Noise Awareness Day, the European Environment Agency (EEA) published a report, ‘The good practice guide on quiet areas’. Quiet areas are those that aren’t disturbed by "unwanted or harmful noise". This

doesn’t just relate to the volume of sound in an area, but rather the nature of the sounds — whether the frequen­cies are particularly harmful or abrasive. The guide gives authorities information on how to identify and protect quiet areas.

The report lists the work already done by several countries to preserve these crucial quiet areas. It highlights that even in cities there are areas with good acoustic quality, places of respite from the cacophony of urban life. For instance, in Oslo, Norway, authorities mapped areas of quiet that can easily be accessed by the city’s locals. In Dublin, Ireland, authorities designated eight quiet areas to be protected from potential sources of noise pollution.

The European Soundscape Award has been created by the EEA and the Noise abatement societies of the Nether­lands and UK to encourage innovation in solving noise problems. This is another step in the process of raising awareness and solving noise pollution problems in Eu­rope.

The effects of poor acoustic environments can be both physical and psychological, creating disrupted sleep pat­terns and stress. As our cities get louder, it is crucial that we are aware of the damage noise pollution can do, and have a quiet place to gain relief.

Source of article

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(This ability helps us react to dangers, for example, or distinguish words in a sentence.) But Wehr’s research extended those findings by showing that, remarkably, the auditory cortex has a separate network of neurons that fire when silence begins. "When a sound suddenly stops, that’s an event just as surely as when a sound starts." Even though we usually think of silences as a lack of input, our brains are structured to recognize them, whenever they represent a sharp break from sounds. So the question is what happens after that moment - when silence continues, and the auditory cortex settles into a state of relative inactivity.

One of the researchers who’s examined this question is a Duke University regenerative biologist, Imke Kirste. Like Bernardi, Kirste wasn’t trying to study silence at all. In 2013, she was examining the effects of sounds in the brains of adult mice. Her experiment exposed four groups of mice to various auditory stimuli: music, baby mouse calls, white noise, and silence. She expected that baby mouse calls, as a form of communication, might prompt the development of new brain cells. Like Bernardi, she thought of silence as a control that wouldn’t produce an effect.

As it turned out, even though all the sounds had short ­term neurological effects, not one of them had a lasting impact. Yet to her great surprise, Kirste found that two hours of silence per day prompted cell development in the hippocampus, the brain region related to the formation of memory, involving the senses. This was deeply puzzling: The total absence of input was having a more pronounced effect than any sort of input tested.

Here’s how Kirste made sense of the results. She knew that "environmental enrichment", like the introduction of toys or fellow mice, encouraged the development of neurons because they challenged the brains of mice. Perhaps the total absence of sound may have been so artificial, she reasoned - so alarming, even that it prompted a higher level of sensitivity or alertness in the mice. Neurogenesis could be an adaptive response to uncanny quiet. The growth of new cells in the brain doesn’t always have health benefits. But in this case, Kirste says that the cells seemed to become functioning neurons. "We saw that silence is really helping the new generated cells to differentiate into neurons, and integrate into the system."

While Kirste emphasizes that her findings are preliminary, she wonders if this effect could have unexpected applications. Conditions like dementia and depression have been associated with decreasing rates of neurogenesis in the hippocampus. If a link between silence and neurogenesis could be established in humans, she says, perhaps neurologists

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