You know about noise (pollution) right?
If not, you would probably not be reading here...
Screaming neighbors. Fighting cats. Traffic. Overflying airplanes.
Or maybe there's just a specific sound that's really irritating for you. Perhaps you don't like listening to Britney Spears - even at a low volume. Or, alternatively, you hate listening to Mozart or the Beatles.
Everyone hates certain sounds.
I'll tell all about you my "favorite" noise sources later on in this blog post.
And I'm also (too) acquainted with what's happening with most noise pollution problems. The more you focus on the noise, the more irritating it gets.
I completely understand.
So what's the solution?
In this 3-part series, I'll tell you exactly what you need to know about reducing noise (pollution).
The first step understanding any problem is being aware that there's something wrong in the first place. This blog post series'' first installment takes that step, teaching you about what noise pollution is as well as some common effects.
With noise, most people assume that it's simply an annoying side issue--not a problem. And yet, noise is a societal problem. An enormous problem. In fact, noise is so omnipresent everywhere in society that it can be called "noise pollution".
Before I dig into the health effects of noise and illustrate you how to deal with it, let's first try to understand how the problem originated in the first place.
I thus arrive at my first installment of the noise pollution series.
Just imagine the difference between the following two situations:
Firstly, envision that you're in the woods. Fantasize about the sound of the wind blowing through against the leaves, water running downstream, and birds that are singing:
Secondly, envisage that you're in the following location:
What's happening in the latter case?
Cars are honking, people are talking loudly (and perhaps even screaming), three different types of music may be blasting in the background, and there's also noise emerging from a construction site.
Moreover, all the noise stays "trapped" in that location due to all the high rise buildings. What's even more amazing is that you're not even consciously hearing all those sounds in the metropolitan city anymore.
You've gotten "used" to such sounds, right?
Even though you might not be consciously hearing noise (in the background) all the time, your health is still affected by that noise.
The gist of my argument in this blog post is that your brain can never fully get used to noise pollution. Instead, you can only deal with noise by removing the source of the noise, or by making sure that less noise ends up reaching your ears.
If you don't get rid of excessive noise, your health automatically suffers.
Before diving deep into the topic of sound and noise though, let's first make sure we're all on the same level.
Let me thus give you a definition of both 1) sound; and 2) noise.
Sound, firstly, is the propagation of waves that are either consciously or subconsciously audible to the brain by using your ears.
Let's explore that definition of sound in some more detail.
Observe that I subsume both conscious hearing of sound and a subconscious hearing of sound under my definition. So, even if you're not consciously aware of a sound, those waves are still registered by your brain.
Why do I include subconsciously hearable sound as well? Well, there are things called "subliminal" sounds, which exceed the human hearing threshold. When subliminal sounds are loud enough, they are still registered by your brain and cause damage...
Another type of sound is infrasound, which falls below the hearing threshold. Windmills, for instance, produce that infrasound that you cannot hear but will affect your physiology.
Secondly, I need to define noise...
But let's first take a step back and look at how others define "noise":
Noise is often defined subjectively nowadays. One common definition, for example, is that noise is "unwanted sound".
That definition does not work for me at all.
Because noise has very objective consequences (for your health) at certain levels of loudness. I've therefore decided to combine the objective and subjective domains of noise into one:
Noise is sound that causes an unhealthy reaction in your body, either due to its loudness, or your (brain's) subjective dislike of the sound.
Let me explain that definition...
On the one hand, certain sounds can cause an unhealthy reaction in your body, independent of whether you like or dislike that sound. The sound of your favorite music at night when it's played hard enough, for example, will lower your sleep quality, even though you might like that music (at some level).
An 80dB sound level at night - even though you've convinced yourself that you've gotten "used" to that sound - will always be damaging.
Some sounds, on the other hand, can create problems independent of their loudness. If your husband is whispering your name to get attention when you're trying to focus on a complex task, the sound can be distracting independent of its loudness.
Your husband is thus creating noise in that instance.
Hearing a baby cry, moreover, will also trigger a response in you, even though the sound may not be very loud.
So overall, if a sound either 1) reaches a certain loudness threshold; or 2) is disliked by you, that sound becomes noise.
(Advanced explanation: some sounds are even inherently disliked by human beings, such as low-toned roars in the animal kingdom, which signal aggression, or the sound of a snake, for example. Those sounds have been ingrained in our very being through millions of years of evolution.)
Now, let's consider the health effects of noise. Noise pollution is not a "side-issue".
What if I told you that through noise pollution:
I'll explore all these effects in detail in a subsequent section.
First, let's have a more precise look at what sound and noise pollution exactly consists of...
Noise pollution does not just happen in modern societies. Instead, noise has been a problem as old as civilization.
Even in ancient Greece, cities allocated specialized areas for merchants and other occupations which are intrinsically associated with noise creation, which were placed outside the city walls.
Ancient Greece: the birthplace of
Western Civilization - and also the first noise laws.
People have certainly been complaining about noise for centuries as well.
Arthur Schopenhauer - a German philosopher who mainly lived in the 19th-century - is known for his interesting rants on noise.
Let me give you a few excerpts.
First, Schopenhauer talks about how noise increases the difficulty of thinking clearly:
"Occasionally it happens that some slight but constant noise continues to bother and distract me for a time before I become distinctly conscious of it. All I feel is a steady increase in the labor of thinking — just as though I were trying to walk with a weight on my foot."
"Noisy interruption is a hindrance to concentration. That is why distinguished minds have always shown such an extreme dislike to disturbance in any form, as something that breaks in upon and distracts their thoughts. Above all have they been averse to that violent interruption that comes from noise."
Some other passages demonstrate Schopenhauer's deep-seated hatred for noise as well. Here's yet another one:
"The general toleration of unnecessary noise — the slamming of doors, for instance, a very unmannerly and ill-bred thing — is direct evidence that the prevailing habit of mind is dullness and lack of thought."
Interestingly enough, despite his flowery language, some of Schopenhauer's claims were scientifically verified in the 20th century: noise does indeed interrupts and lowers your higher-level thinking ability.
In that time you had to rely on intuition to know whether someone is too loud or not. Today is different, fortunately. Through modern day scientific instruments, you're able to assess sound levels extremely reliably.
By measuring "decibel" level of sound...
(Advanced explanation: in the early 19th century, the field of psychology was still subsumed under philosophy, and strict psychological experiments were still almost a century away. Measurement of sound was not standardized nor well developed back then.)
Today, "decibels" (dB) are the most universally used measurement-unit for sound levels.
To be exact, dB measures the loudness of a sound. dB measurements commonly range from 0 to (roughly) 200. The higher the dB measurement, the louder the sound.
What's very important to understand about dB measurements is that it's a mathematically "logarithmic" scale. Let me explain what the word "logarithmic" means in relation to sound - which is easiest demonstrated through an example:
Assume that you're exposed to a sound of 30dB - which equals the sound levels of standing in the woods when nothing exciting really happens. Sure, you might hear some insects, the wind blowing, and whistling leaves, but overall, it's pretty quiet.
If you compare that 30dB measurement to a 40dB measurement, the sound doesn't get 33% louder. Instead, for every 10dB increase in sound, the loudness increases with a factor of 10. Phrased differently, as there's a 10dB difference between 30dB and 40dB, a 40dB sound level is 10 times as loud as 30dB.
Many people, when comparing 30db with 60dB, would think that 60dB is twice as loud as 30dB. Let's calculate whether that assumption is true. First, observe that there's a 30dB difference between 30dB and 60dB. For every 10dB increase, the sound becomes 10 times as loud. A 30dB increase thus makes a sound 10*10*10 (10^3) = 1,000 times as loud.
The dB scale is developed that way to be easily express sound levels without having to work with extremely large numbers. A 70dB and 140dB sound level have a 10,000,000-fold difference in sound intensity.
Why that scale?
Comparing 30dB to 150dB, for example, would force you to deal with many digits when doing calculations. A dB logarithmic scale is an easy-to-use tool to efficiently express loudness levels.
Let me attempt to read your mind though:
You must be thinking by now: "Bart, how loud are my neighbors during the nighttime?"
Let's find out...
I'll give you some examples of loudness at each dB level:
10dB - Your breathing, the Grand Canyon at night, or the sound of dropping a pin
20dB - Leaves in the forest, whispering of a single person, a rural area with snow
30dB - A common quiet rural area sound level, or running computer.
40dB - Multiple people whispering in a classroom, library sound, birds singing
50dB - Regular conversations, very light traffic, background music, dishwasher
60dB - Air conditioner, bypassing car at 50 miles per hour, restaurant conversation
Now, at 65dB noise can already become damaging (if you're exposed for a long time):
70dB - Showering, music at regular-loudness, bypassing trucks, vacuum cleaner
80dB - Drilling machine, your morning alarm clock, a bypassing freight train
90dB - Low-flying Boeing 737, mp3 player, lawnmower
100dB - Subway car, food processor, airplane take-off, motorcycle
110dB - A rock concert, jackhammer, or an auto horn at a 3-yard distance
120dB - Classroom filled with screaming children, thunder impact
130dB - Football stadium noise peak
At this point, noise starts to generate ear-pain:
140dB - Jet engine take-off, firecrackers
150dB - Rock concert peak near speakers, fighter jet take-off
160dB - Weapons firing (such as a shotgun),
180dB - Rocket launch
194dB - Official maximum sound level - at this point, a sound is converted into "shockwaves".
Birds singing in the morning at 40dB.
A thousand times less loud than bypassing trucks
So how about your noisy neighbor? Let's analyze that neighbor's sound level.
Depending on his location, he's probably putting out 60-90dB from the source. Fortunately, some of that noise is filtered by the walls of your house...
What can you conclude from seeing that list of noise levels?
Let's return to our earlier example of comparing the forest to the city in terms of noise levels.
Sound levels in the forest are located at a 40dB level--the inner city, with bypassing cars at 50 miles and hours, and trucks, ends up with sound levels of roughly 60 to 70dB.
Let's assume - for the sake of argument - that cities have sound levels of 60dB. In that case, there's a 20dB difference between the forest and an inner-city.
Again, it's very important to realize that 60dB is not 50% louder as 40dB.
Instead, a 20dB difference entails a 10^2 (10*10) = 100 fold increase in the sound level. Phrased differently, the energy of sound input of your ears is 100 times as strong in an inner city compared to a forest.
And the example does not even take even louder metropolitan cities into account, that often have sound levels up to 80-90dB.
Absolutely amazing (or crazy) difference right?
That conclusion tells you something about human perception. Even though it might seem or feel that there's no extreme difference between an inner-city and forest in terms of sound levels, the difference is absolutely enormous.
So, what happens next? Let's say you're living in a big city with lots of noise? In that case, your ears and brain have to process that sound. While I'm taking a deep-dive into the health consequences of noise soon, let's first put the noise levels of cities into more perspective...
Let's, therefore, explore the sound levels of several cities, to help you understand how much sound is commonly present there...
You might be sceptical of my assessment, but I've got lots of solid data to back up my claims:
The mean street-level sound in New York city is 70dB+, in Hong Kong sometimes exceeds the 90dB level. Even during the nighttime, sound levels in Hong can approximate 65dB.
Such noise levels have also been found in a smaller Turkish city during the daytime. A 70dB+ level is thus by no means limited to big metropolitan cities.
Other examples of smaller cities?
In Kalamazoo County, Michigan, average daytime noise levels approached 80dB. 70% of people exceeded safe sound level exposure thresholds during the daytime.
You might be thinking: "but those measurements were taken outside".
You're absolutely correct in that assessment.
I've also got a reply to that statement though...
The difference between outdoor and indoor noise levels have also been studied: in Tokyo, there's only a 10dB difference between outdoor and indoor environments. Noise levels of 55dB outside already make 50% of people feel uncomfortable inside - let alone 80 or 90dB.
And yet, residents, industrial workers, and office employees are routinely exposed to 60dB indoor sound levels. Why? Again, 70dB outside translated to 60dB that's commonly experienced inside...
In buildings for some purposes, lots of noise is also generated indoor.
Noise levels in classrooms in Greece and Hong Kong reach as high as 70dB during the day. In London, that's 60dB, in Sweden, 40-70dB.
In many offices too, noise levels easily reach 60-80dB levels.
The same levels, or worse. Noise pollution is thus not restricted to being outside in the city. Noise is everywhere in modern society...
The height of human civilization?
Or the precursor to its downfall?
Of course, the difference between sound levels of indoor and outdoor environments varies for different building types.
Different types of windows (and whether they're opened), walls, ventilation shafts, ceiling types, building height, and doors, all influence how much outdoor sound penetrates indoor.
Opened windows allow for a 10dB difference between outdoor and indoor sound levels. Tilted windows lower that value, and closed windows prevent a sound buildup of as much as 30dB (if you're really stopping all air flow).
Due to the many variables that influence how much sound penetrates into buildings, there's strict no algorithm or formula that can adequately calculate how buildings influence sound levels.
It's, therefore, best to determine the net amount of outdoor noise pollution that reaches indoor on a case-by-case basis. You thus have to measure levels inside buildings. A decibel meter phone app can do the trick for that measurement!
But there's yet another problem:
While closing your windows inside a city might sound smart to stop noise from entering, you'll build up lots of toxic air through that method.
Keeping your windows closed also creates CO2 build up and lowers oxygen levels so that your breathing and brain function is impaired.[73; 74; 75] It's best to let CO2 leave your home continually, even during the nighttime.
No airflow in your home equals improper breathing...
In an inner city, you're thus confronted with a double bind: choosing between either more noise pollution or more air pollution.
Neither option is optimal...
So, how are indoor noise levels influenced?
The net-level of noise you're exposed to depends on many variables such as:
I'm not going into full detail of how quick or slowly dB readings decline with distance, as that is a complex calculation.
The bottom line is that noise calculations can be complicated. Again, if you want to know your indoor noise levels, you have to measure them. There's a measurement mini-guide included in the "Frequently Asked Questions" section at the bottom of this article.
(And if you want more information on the physics of sound, just read this book.)
Here's where things get even crazier...
The numbers are higher than you think:
So, what's your conclusion? Is the problem of noise pollution improving or getting worse?
Data clearly demonstrates the latter case to be true, despite governments' attempts at curbing noise.
Let's look at such legislation:
In the EU, proposals have been made to set the limit of noise pollution at a 40dB maximum for night times.
Noise affects you differently during the day and night. The sound of a bypassing truck or a vacuum cleaner, for example, might be somewhat noticeable during the day but can be extremely irritating at night.
During the nighttime, a small amount of noise can already wake you up. Some sources even argue that the 40dB threshold is already too high, and that sound levels between 35 and 40dB already impair sleep quality.
And yet, noise pollution is barely taken into account by most healthcare experts in modern society. That assessment is very strange because noise pollution is the most common complaint that people have regarding their living environment.
So, it's not water pollution or air pollution that irritates people most, but noise pollution.
Here they are:
But that's not all of course:
Church bells, wind turbines, and neighbors throwing parties or people fighting are other reasons why noise pollution exists. Lawnmowers are a frequent source of noise as well, although newer models emit closer to a 70dB sound level instead of the 90dB sound level of the past.
Going clubbing, to a bar or a restaurant? You'll have a 50% chance of getting exposed to excessive sound levels.
Another crazy fact?
Intensive care units are the most damaging noise pollution locations in hospitals.
Additionally, the general sound levels in hospitals have been increasing 10dB in the last few decades. Sound levels in hospitals now commonly exceed the WHO prescribed maximum noise threshold by as much as 20dB.
Quite a dangerous place to spend your time, hospitals...
Fighting cats: nature's original form of
urban noise pollution.
Now you've learned about the dB scale and how noise is omnipresent in our modern society, in the next installment I'll have a look at noise's health effects on your body.
Things will get worse before they get better...
I hope you're convinced that noise pollution is a huge potential issue.
In fact, more and more places of this planet now have the problem of noise.
I hope that with this blog post I've made you more aware that there's a problem in the first place. That thesis becomes much clearer once you read the second installment of this series, regarding the health effects of noise pollution.
And yet, from a very basic emotional or feeling perspective, you probably already know there's something to noise. The issue is that you never noticed how intricate the problem was.
Becoming consciously aware is very simple as well though: download a decibel meter on your smartphone and begin measuring your environment. Those measurements lead to data, that data leads to understanding, and hopefully, that understanding leads to better choices.
You deserve the best!
This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - Cum Laude), and Clinical Health Science (MS), and is currently a health consultant at Alexfergus.com.
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