It’s no secret that noise is a bad thing. It can make us feel uncomfortable and annoyed, and it can even be detrimental to our health.
But how much do we really know about noise and the problems it poses? For example, do you know the difference between sound and noise?
Existing as a pressure wave that is created from vibrations in the environment or an object, a sound can be anything that is perceived by the human ear. As an integral part of our lives, sound comes in various forms — whether it is the singing of birds or the cascading of water — and is not necessarily just one specific vibration or frequency1.
Noise, on the other hand, is simply unwanted sound2. Reactions to noise can be a complicated affair, as there is no physical distinction between sound and noise. This makes noise highly contextual, and is affected by different characteristics such as volume, frequency, and pitch, as well as how much control we have over it.
This could explain how a fan of heavy metal might enjoy the music while someone else might find it unbearable, or why the pleasant melody of wind blowing through the trees could become bothersome when it prevents you from clearly understanding the person you are having a conversation with.
In other words, a single sound could be either noise or not noise depending on what you want to hear. This is referred to as listener intent.
What is noise?
Imagine this: You are watching TV when someone comes up and starts talking to you. Which is the noise — the sound from the TV or the person’s voice? It all depends on what you want to hear. Listener intent helps you focus your attention on your desired sound while reducing background noise3.
However, loud noise can still be overwhelming, and becomes particularly problematic when it disturbs important activities such as sleep, learning, and work.
The World Health Organization (WHO) recommends less than 30 A-weighted decibels (dB(A)) of noise in bedrooms and less than 40dB(A) outside of bedrooms for good quality sleep. A-weighted decibels is a system of measuring sound levels with the same sensitivity to different frequencies as the average human ear4. For reference, a person whispering in a quiet room is approximately 25dB(A)5.
Noise can affect your health
Exposure to noise levels above 40dB at night can result in sleep disturbance and awakenings. Good quality sleep is important for ensuring that our brain functions well during the day. It also plays a critical role in allowing our bodies to repair and recover themselves from a tough day’s work, in order to continue performing at peak condition. Therefore, sleep disturbance could lead to adverse effects to the human body.
For example, it could impact the hormonal changes that regulate our glucose levels as we sleep, which would lead to reduced glucose tolerance and increase the risk of type 2 diabetes6. What’s more, people experiencing interrupted sleep may find themselves at greater risk of depression, putting a strain on their mental health7. At noise levels above 55dB, elevated blood pressure and ischaemic heart disease may occur8, which can ultimately lead to heart attacks.
In fact, a WHO study discovered that at least one million healthy life years are lost every year in Western Europe as result of exposure to environmental noise9. This positions noise as the second largest environmental cause of ill health, after air pollution10. On top of that, a UK study showed that exposure to noise above the recommended levels resulted in an additional 1169 cases of dementia, 788 cases of stroke, and 542 cases of heart attack in a single year11.