Understanding noise pollution.

Early single glazing in New Zealand used 3-4mm thick glass, which did a great job at preventing predators and rain from entering the home, but did little to insulate against external temperatures and noise pollution.  As towns and cities have grown in size, more and more people ask us, "does double glazing reduce the noise in my home?"

Noise pollution is a form of environmental pollution characterized by the presence of unwanted or excessive sound that has a harmful or annoying effect on human health or the environment.

According to the World Health Organization (WHO), noise pollution is a serious health hazard that can cause a range of adverse health effects

One of the most well-known effects of noise pollution is hearing loss. Exposure to high levels of noise can damage

the delicate hair cells in the inner ear, leading to permanent hearing loss. The WHO estimates that approximately 1.1 billion young people around the world are at risk of hearing loss due to exposure to loud music and other sources of noise pollution (https://www.who.int/news-room/fact-sheets/detail/deafness-and-hearing-loss).

A study published in the International Journal of Hygiene and Environmental Health found that “long-term exposure to road traffic noise is associated with an

increased risk of myocardial infarction” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107046/).

Noise pollution can also have an impact on mental health. Chronic exposure to noise pollution can cause stress, anxiety, and depression, which can in turn have a negative impact on physical health.  Noise pollution can impact our overall quality of life. Exposure to unwanted noise can be annoying, distracting, and disruptive, making it difficult to relax and enjoy home comfort.

How does sound move through glass?

Sound travels through the glass in two ways:

–  Vibration – When sound waves hit a glass surface, the glass vibrates at the same frequency as the sound waves

–  Transmission – Sound waves can pass through the glass itself if the glass is thin enough or if it is not dense enough to block the sound. This is more likely to happen with higher-frequency sounds, which have shorter wavelengths and can pass through smaller openings.

When glass vibrates it then creates new sound waves that travel through the glass. This is known as sound transmission through vibration.

One phenomenon that plays a significant role in sound transmission through materials is

What is the Coincidence Dip?

The Coincidence Dip is a frequency range at which the sound transmission through a material is significantly reduced due to a coincidence between two types of waves:

–  the sound waves that are transmitted through the material

–  the vibration waves that occur within the material itself.

When sound waves pass through the glass, they create vibrations in the glass that can interfere with the initial or primary sound waves. At a certain frequency range, the wavelength of the primary sound waves becomes equal to the distance between the two surfaces of the material, causing the primary waves and the secondary waves to interfere destructively with each other.  This destructive interference results in a significant reduction in sound transmission at that frequency range.

How to reduce soundwaves moving through the glass?

As with solar energy, when a sound wave hits glass, part of the wave is reflected, part is absorbed and the remainder is transmitted through the glass to the other side.  To reduce the amount of noise entering the home, the sound wave needs to meet with some resistance to prevent the sound being transmitted through the glass.

There are a variety of options available to provide that resistance:

–  Thicker/denser glass – the thicker the glass, the more the waves have to move through which slows the transmittance down.

–  Laminated glass – adding a plastic (PVB – polyvinyl butyral) interlayer provides a small amount of sound damping but this is primarily used for safety and UV reduction

–  Double glazing – two panes of glass provide the benefits of density, but double glazing also increase sound reduction due to the gas inside the space of the double glazing that dampens the vibrations of the first pane of glass before those vibrations reach the second pane.

Introducing SuperTherm Protect™.

SuperTherm Protect™ is double glazing, so it has two panes of glass increasing the thickness of glass that the sound waves must move through.

SuperTherm Protect™ has the additional benefit of a high-quality acoustic laminate that has a special noise damping interlayer that that provides exceptional acoustic attenuation (reduction or loss of acoustic energy through the glass).

An acoustic film used inside the laminate acts as a dampener, preventing the glass panes from resonating with each other, ensuring a consistent level of sound insulation.

 

Have a look at the below chart to see the improved performance using SuperTherm Protect™ over traditional single and double glazing.