Hear Your Pollution

We all talk about the many different avenues for visible pollution. But there is another form of pollution just as harmful and invasive, yet is invisible, noise pollution. Noise is defined by the EPA as any unwanted or disagreeable sound and is often dismissed simply as a “nuisance.” The air around us is constantly filled with sounds, yet most of us would probably not say we are surrounded by noise.  Though for some, the persistent and escalating sources of sound can often be considered an annoyance.  This “annoyance” can have major consequences, primarily to one’s overall health. But to understand noise pollution you have to understand how it is measured.

The loudness of a sound (also called sound pressure level, or SPL) is measured in logarithmic units called decibels (dB).Decibels, originating from methods used to quantify signal loss in telegraph and telephone circuits by the Bell Telegraph Company,  are a ratio, measured as ten times the base-10 logarithm of the ratio of measured power to a reference power level. This means that an increase of 10 dB represents a 10-fold increase in sound intensity, an increase of 20 dB represents a 100-fold increase in intensity, a 30-dB increase represents a 1,000-fold increase in intensity, and so on. When sound intensity is doubled, on the other hand, the SPL increases by only 3 dB. For example, if a construction drill causes a noise level of about 90 dB, then two identical drills operating side by side will cause a noise level of 93 dB. On the other hand, when two sounds that differ by more than 15 dB in SPL are combined, the weaker sound is masked (or drowned out) by the louder sound.

atl
Noise Pollution map of Metro-Atlanta area

Now that we have established that, noise pollution is managed by the EPA under the Title IV of theClean Air Act (Noise Pollution), The Noise Control Act of 1972 (42USC7641) and The Quiet Communities Act of 1978. Studies have shown that there are direct links between noise and personal health.  Problems related to noise include stress related illnesses, high blood pressure, speech interference, hearing loss, sleep disruption, and lost productivity. To combat this in the workplace the Occupational Safety and Health Administration set up industrial noise criteria time limit.

Daily maximum noise exposure permitted by the
U.S. Occupational Safety and Health Act of 1970

sound level (decibels)

maximum hours per day

115
110   ½
105   1
100   2
  97   3
  95   4
  92   6
  90   8

 

These noise criteria are set in law for the workplace yet there are no noise criteria set for an equally as important setting, the classroom. Average classroom dB ratings can range from 45 to 82 dB. According to the American National Standard on Classroom Acoustics, the noise level in empty classrooms should not exceed 35 decibels­

SPL
Perceived loudness of different frequencies to the human ear. Notice the dip around 3.5k. That is our most sensitive hearing frequency range. The average baby’s cry occurs around 3.5k

The impacts of excessive noise vary according to the age of the students because the ability to focus on speech is a developmental skill that evolves with the maturation of the brain and mastery of language. Because the auditory mechanism does not fully mature until age 13 to 15 years, young children … require better acoustical environments than do adult listeners to achieve equivalent word recognition scores. (Anderson, 2004, p. 119). This can be a reason behind why noise pollution in the classroom goes unnoticed, the adults don’t perceive it the same way. They can’t measure from a child’s developmental perspective.

One study (Stansfeld et al. (2005)) assessed 2,844 children ages 9 to 10 in 89 schools located in the United Kingdom, Spain, and the Netherlands in 2002. Schools in all three countries were selected on the basis of increasing levels of exposure to aircraft and traffic noise. The selected schools were matched by students’ socioeconomic status, the primary language spoken at home, and other factors. External noise was measured, and reading comprehension was assessed using standardized and normalized tests routinely used in each country. This study found that chronic exposure to aircraft noise “was associated with a significant impairment in reading comprehension…. [A] 5-decibel difference in aircraft was equivalent to a 2-month reading delay in the United Kingdom and a 1-month delay in the Netherlands” (Stansfeld et al., 2005, p. 1946).

Fortunately, more and more schools, as well as office buildings, living quarters etc, are being built with the acoustical engineering in mind. LEED assessment and certification involves a section devoted to measuring a buildings “acoustical performance”. To achieve maximum rating through this a building must have:

  1. Unoccupied classroom levels not exceeding 35 dBA
  2. The signal-to-noise ratio (the difference between the teacher’s voice and the background noise) should be at least +15 dB at the child’s ears.
  3. Unoccupied classroom reverberation must not surpass 0.6 seconds in smaller classrooms or 0.7 seconds in larger rooms
  4. ANSI S12.60-2002, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools standard

 

7464d9d14968f4c97d3504e14d8f6cd1
An example of an acoustically treated classroom. Cloud diffuser and absorption panels are featured on the ceiling and wall. 

 

Sound treatment is relatively cheap and can be installed post development. Leaving room for potential on an individual room basis; installing diffusers, absorbers or maskers. However, the ease and readiness for schools to will look weary into the future; as true acoustic design and engineering are hard, laborious and therefore expensive projects. Unfortunately, expensive and public school system rarely goes hand in hand.

 

Questions?

  1. Have you personally experienced the negative effects of a loud classroom?
  2. Does your academic life at? Such as studying in loud environments.
  3. Why does this not seem to be a hot-buttom question in childhood development?
  4. Where do you place auditory health in your daily life?
  5. Do you were earplugs at concerts?
  6. Should school systems be held responsible for acoustic quality in classrooms?

Sources

VIP, P. B. (n.d.). Too loud to learn: Do schools ignore the impact of noise pollution on kids? | Get Schooled. Retrieved November 26, 2017, from http://getschooled.blog.myajc.com/2017/05/21/too-loud-to-learn-do-schools-ignore-the-impact-of-noise-pollution-on-kids/

Woolner, P., & Hall, E. (2010, August). Noise in Schools: A Holistic Approach to the Issue. Retrieved November 28, 2017, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2954580/

Classroom Acoustics: Overview. (n.d.). Retrieved November 28, 2017, from http://www.asha.org/Practice-Portal/professional-issues/classroom-acoustics/

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5 thoughts on “Hear Your Pollution

  1. I would be curious to see how these levels have changed over the past hundred years for various regions. Also are there any impacts of this noise pollution on wildlife? Can those impacts be separated from the obvious impacts of the machines and population centers that make the noise? This was a very interesting and thought provoking post.

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  2. This is just a reminder of how energy comes in different forms. As more and more humans inhabit our planet, energy of all kinds will be altered. However, noise pollution is new to me. I think it’s interesting that the EPA already set restrictions on it.

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  3. This is an interesting topic that many people would not think about. I learned the hard way the noise pollution level for a residential neighborhood in Athens. One night my roommates were having a casual “jam-sesh” in their words when the police rolled up to the garage. Apparently instead of an SPL level it’s just if the noise can be heard from X feet away. Thanks for the article.

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  4. Thanks for writing about this topic; it is something that I have never thought about before. I just assumed that noise was something you could get used to once acclimated to it. I never would have thought about noise being regulated, although that does make sense. I’d like to know if noise is something that affects some people more than others. Growing up, my dad constantly noticed sounds outside the house like barking dogs and yard tools while the rest of my family never even noticed them.

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