Jane Embury looks at how glass absorbs sound.
During COVID-19, we became used to the sound of silence.
There were fewer cars speeding past our front windows. Fewer aeroplanes in the skies above.
Now, with more cars on the road and planes in the air, the sound of silence has been replaced with the sound of sound.
But how we perceive sound is personal and subjective.
Some people hate silence. Others love the tranquil sound of waves breaking on a beach.
But most of us hate the noise that leaks from someone’s earphones on a bus or train.
In the UK, noise is defined as being “a sound, especially one that is loud or unpleasant or that causes disturbance.” The USA defines it as “unwanted or disturbing sound.”
The simple difference is that sound becomes noise when it interferes with normal activities such as sleeping or conversation.
Unwanted noise probably affects most of us every day. Usually, it’s just temporary and annoying.
However, noise can be more than just an irritant. Research demonstrates that there’s a link between noise and health problems. Those include stress related illnesses, high blood pressure, and sleep disruption.
Lack of sleep may also have an unexpected impact on our waistlines. Research in Sweden suggests that disrupted sleep makes people less willing to exercise, and more likely to put on weight.
So, it may not be the Danish pastries that you ate to cope with lockdown. It could be the people upstairs playing loud music at 2am.
In the developed world, according to the World Health Organisation, as many as 15% of the working population is exposed to sound in excess of 85 decibels.
In the UK, exposure to noise has been linked to impaired reading comprehension in children.
For the workplace, noise pollution has an impact on staff morale, efficiency and productivity. One study in Australia found that a lack of sound privacy was the biggest drain on employee morale.
Prosaically, we perceive noise either physiologically or psychologically. The former is when we simply hear the noise. The latter when we take the trouble to listen to the noise.
Put another way, it’s the difference between listening to our own music and being forced to listen to someone else’s.
There are, of course, a number of ways in which sound can be reduced – from better office layout to sound-proofing. Indeed, providing a workplace free of unacceptable noise intrusion is a legislative requirement.
Often overlooked, one sound-proofing material is glass – either for external glazing or as internal screens.
Glass controls noise by reflecting the noise back towards the source, and absorbing the noise energy within the glass.
Noise pollution can come in a variety of low, medium or high frequency sounds. Higher pitched sound, carried by short sound waves, are easier to absorb. Noise at lower frequencies, for example traffic noise, is less easy to deal with.
It’s therefore important to choose the correct acoustic glazing type, to best deal with the frequency or pitch of the noise to be absorbed.
Sound insulation within a glazing system can be achieved by building in cavity space between panes of glass or thicker glass. It also means using an efficient insulating window frame or utilising specially laminated acoustic glass.
Acoustic glass is a sandwich of two or more sheets of glass, heat or pressure bonded together with one or more interlayers. The interlayers act as a noise damper, weakening the energy of the sound waves as they travel through the glass.
Glass does have other benefits because natural light matters. Research has found that people working under artificial light become sleepier earlier than those who work in natural light.
In addition, studies demonstrate that people work best when they have a view of the external world, on top of the ambient light from it.
Glass walls help light flood in, bringing the outside inside, and psychologically connecting us with the world beyond our office.
Although Wrightstyle’s advanced glazing systems were primarily developed to stop fire and toxic gases they also reduce or eliminate noise pollution.
In the same way that specialist glazing systems provide fire compartmentation, they also compartmentalise sound. That’s either from curtain walling shutting our external noise, to internal glazed partitioning and doors.
Our systems to do just that can be found in a variety of settings – from national laboratories to schools, and from offices to universities.
Sometimes it’s better to listen to the sound of silence.